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International Scientific-Technical and Production Journal
December
2009
# 12
English translation of the monthly «Avtomaticheskaya Svarka» (Automatic Welding) journal published in Russian since 1948
Founders: E.O. Paton Electric Welding Institute of the NAS of Ukraine
International Association «Welding»
Editor-in-Chief B.E.Paton
CONTENTS
Editorial board:
Yu.S.Borisov V.F.Khorunov
A.Ya.Ishchenko I.V.Krivtsun
B.V.Khitrovskaya L.M.Lobanov
V.I.Kirian A.A.Mazur
S.I.Kuchuk-Yatsenko
Yu.N.Lankin I.K.Pokhodnya
V.N.Lipodaev V.D.Poznyakov
V.I.Makhnenko K.A.Yushchenko
O.K.Nazarenko A.T.Zelnichenko
I.A.Ryabtsev
International editorial council:
N.P.Alyoshin
U.Diltey
Guan Qiao
D. von Hofe
V.I.Lysak
N.I.Nikiforov
B.E.Paton
Ya.Pilarczyk
P.Seyffarth
G.A.Turichin
Zhang Yanmin
A.S.Zubchenko
(Russia)
(Germany)
(China)
(Germany)
(Russia)
(Russia)
(Ukraine)
(Poland)
(Germany)
(Russia)
(China)
(Russia)
Promotion group:
V.N.Lipodaev, V.I.Lokteva
A.T.Zelnichenko (exec. director)
Translators:
A.A.Fomin, O.S.Kurochko,
I.N.Kutianova, T.K.Vasilenko
PE «Melnik A.M.»
Editor
N.A.Dmitrieva
Electron galley:
I.S.Batasheva, T.Yu.Snegiryova
Publisher: International Association «Welding»
SCIENTIFIC AND TECHNICAL
Makhnenko V.I., Poznyakov V.D., Velikoivanenko E.A.,
Makhnenko O.V., Rozynka G.F. and Pivtorak N.I. Risk of cold
cracking in welding of structural high-strength steels ............................ 2
Gorban V.F., Kharchenko G.K., Falchenko Yu.V. and
Petrushinets L.V. Investigation of joints of titanium aluminide
with titanium alloy VT8 produced by diffusion welding ........................... 7
Sabokar V.K., Akhonin S.V., Petrichenko I.K. and Yasinsky A.V.
Pressure welding of titanium aluminide to other titanium alloys ............ 10
INDUSTRIAL
Welding and Cutting 2009. Essen, Germany, 14--19
September 2009 ................................................................................. 13
Shelyagin V.D., Khaskin V.Yu., Mashin V.S., Pashulya M.P.,
Bernatsky A.V. and Siora A.V. Features of laser-MIG welding
of high-strength aluminium alloys ........................................................ 21
Zelenin V.I., Kavunenko P.M., Tisenkov V.V., Teplyuk V.M.,
Poleshchuk M.A., Lebed V.D., Lipisy V.I., Bondarev S.V.,
Gavrilov S.A., Olgard N.T. and Cheburov S.A. Application of
plasma-arc metallisation for restoration of wheel pairs ......................... 28
Tsaryuk A.K., Ivanenko V.D., Volkov V.V., Mazur S.I.,
Trojnyak A.A., Vavilov A.V., Kantor A.G. and Volichenko N.P.
Repair welding of turbine case parts from heat-resistant steels
without subsequent heat treatment ..................................................... 32
BRIEF INFORMATION
Address:
E.O. Paton Electric Welding Institute,
International Association «Welding»,
11, Bozhenko str., 03680, Kyiv, Ukraine
Tel.: (38044) 287 67 57
Fax: (38044) 528 04 86
E-mail: [email protected]
http://www.nas.gov.ua/pwj
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KV 4790 of 09.01.2001
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Copies of individual articles may be obtained
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© PWI, International Association «Welding», 2009
Lankin Yu.N. and Sushy L.F. Electrical conductivity of slag
pool in electroslag welding with wire electrode .................................... 37
News .................................................................................................. 39
NEWS
International Conference «Improvement of Turbine Plants
Using Methods of Mathematic and Physic Modelling» .......................... 40
Seminar on welding technologies «Full Readiness to Excelent
Welding of Steel» ................................................................................ 41
International exhibition «Weldex/Rossvarka-2009» ................................ 44
International Scientific and Technical Conference «Problems
of Welding, Related Processes and Technologies» ............................... 46
International Conference «High Mat Tech» ........................................... 48
Index of articles for TPWJ’2009, Nos. 1--12 ......................................... 49
List of authors ..................................................................................... 53
RISK OF COLD CRACKING IN WELDING
OF STRUCTURAL HIGH-STRENGTH STEELS
V.I. MAKHNENKO, V.D. POZNYAKOV, E.A. VELIKOIVANENKO, O.V. MAKHNENKO,
G.F. ROZYNKA and N.I. PIVTORAK
E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
Mathematical model of the risk of cold cracking in welding of structural high-strength steels is considered. The model
is based on distributed data on the state of microstructure, content of diffusible hydrogen and stressed state in elementary
volumes within the welded joint zone. It is shown that the model makes it possible to more precisely evaluate the local
conditions of cold cracking on the basis of the above parameters.
K e y w o r d s : arc welding, low-alloy high-strength steels,
brittle fracture, cold cracks, diffusible hydrogen, microstructure, stressed state, probability model
It is a known fact that the presence of quench structures, diffusible hydrogen and tensile stresses [1] are
conditions that induce cold (hydrogen) cracks in welding of structural steels. As to the quantitative characteristics of the specified conditions, at present it is
possible just to approximately evaluate critical values
of the corresponding characteristics, allowing for locality of cold cracking processes, presence of a significant gradient of changes of these characteristics in a
zone of welding heating, their strong mutual effect
and other factors, by limiting their extreme demonstrations with almost no account for their mutual effects. Meanwhile, development of the methods (experimental and calculation) for determination of distributed parameters of the above characteristics in
welding of different joints on structural steels, as well
as the trends to optimization of the techniques to prevent cold cracks require development of more precise
criteria of the risk of their formation.
It can be shown that many recent approaches [1]
based on such integral characteristics as carbon
equivalent in the HAZ [1], content of hydrogen in
filler metal, degree of restraint and thicknesses being
welded, used as the quantitative conditions for microstructure, diffusible hydrogen and effective stresses
are of a very general character. They are far from
providing an ambiguous determination of the quantitative characteristics of the conditions causing cold
cracking at certain parameters of welding heating. It
has been proved in recent decades, due to the development of the «Sysweld» and other types of computer
systems, which help to obtain the calculation information on the distributed characteristics in the weld
and HAZ metals regarding the cold cracking conditions, that zones of potential cold cracks do not always
have the most extreme combinations of volumes of
quench microstructures, content of diffusible hydrogen and level of tensile stresses. Often the zones with
a maximum volume of martensite and content of diffusible hydrogen are within the compressive zones, or
the zones with high tensile stresses have a purely bainitic microstructure and low level of diffusible hydrogen, i.e. they are not potential centers of cold cracks.
In other words, the proper, physically substantiated
criteria that quantitatively connect, on the level of
the distributed parameters, the necessary conditions
for cold cracking to occur in welding heating of structural steels under consideration, are required.
An approach for development of such criteria,
based on the following factors, is given below:
• probability assessment of the risk of cold cracking
is performed in a specified area of a welded joint
(certain region of the fusion zone or HAZ);
• initiation and propagation of cold cracks take
place by the brittle fracture mechanism, i.e. determined by correspondent normal stresses σjj(x, y, z)
at a point with coordinates x, y, z, acting in an area
with normal j and corresponding characteristic of resistance of a material, Aj(x, y, z), to brittle fracture
formation.
Àj is a function of microstructural state and content
of diffusion hydrogen for a given steel.
The probability of brittle fracture in specific volume V, in compliance with the Weibull theory, is determined by dependence
  σ -- A η



jj
j
Pj(V) = 1 -- exp --∫ 
 dV/V0,
 V  Bj 



(σjj > Aj). (1)
In (1), integration is carried out only with respect
to elementary volumes dV, where σjj > Aj, and Aj, η
and BjV1/η
are the Weibull distribution
parameters.
0
__
As a rule, η = 4.0, and Aj and Bj = BjV1/η
are deter0
mined experimentally.
__
The values of Bj depend on the size of the volume
V along the section with normal j (Figure 1). If
stresses σjj and material resistance Aj in length lj of
this volume change but slightly, then a change of
dV = ljdF can be made in integral of expression (1),
where F is the cross-section area of volume V.
Accordingly, the following will be obtained instead of (1):
© V.I. MAKHNENKO, V.D. POZNYAKOV, E.A. VELIKOIVANENKO, O.V. MAKHNENKO, G.F. ROZYNKA and N.I. PIVTORAK, 2009
2
12/2009
Figure 2. Schematic of root weld with longitudinal (1) and transverse (2, 3) cracks in welding sample (4) δ thick and 2L wide,
fixed with side fillet welds to plate (5) δp > > δ thick
Figure 1. Schematic of cold cracking in fusion zone (FZ) and
heat-affected zone (HAZ): 1 ---- longitudinal crack with normal y;
2---- transverse crack with normal x; 3 ---- underbead crack with
normal z (longitudinal)


Pj = 1 -- exp --∫
 F

 σjj -- Aj 

 -

 Bj /l1/η
j 


η


dF.


Application of the described approach for description of cold cracking conditions in welding of the butt
weld root pass in a typical welding sample of steel
14KhG2SAFD with thickness δ = 18 mm thick is
shown below (Figure 2). The CCT diagram is also
given below (Figure 3). Arc welding with ANP-10
electrodes was used for that. Chemical composition
of the base and filler metals is given in Table 1.
In Figure 2, initial heating temperature T0, hydrogen content H filler in filler metal and restraining base
L were variable conditions for welding of the butt
weld sample. Arc welding of the root pass was carried
out under the following conditions: I = 140--150 A,
Ua = 24 V, and vw = 7.2--7.5 m/h. Values of variable
parameters T0, Hfiller and L for different variants of
butt welding are given in Table 2.
Welding of ten samples was performed for each
variant. The probability of cold cracks of the type
shown in Figure 4 was determined on the results of
their examination. Further examinations related to
determination of temperature fields in welding, microstructural changes, hydrogen diffusion and stresses
in FZ and HAZ were carried out by using numerical
methods based on the corresponding mathematical
models developed by the E.O. Paton Electric Welding
Institute [2]. These models are based on the principle
of sequential tracing of evolution of temperature
fields, microstructural changes, stresses and strains,
as well as diffusion of hydrogen from a correspondent
initial distribution in the filler and base metals, allowing for changes in solubility and diffusion coefficients depending on the temperature, as well as microstructure changes [2].
Not dwelling on peculiarities of such modeling for
the steel under consideration, the thermal-physical
and mechanical properties of which are well known
(2)
From which
 l0 1/η
Pj(lj) = 1 -- [1 -- Pj(l0)]   ,
 lj 
 
(3)
where Pj(l0) is the probability of cold cracking in
plane with normal j in length l0 of volume V. In a
particular case, where normal j is directed across the
weld, then lj and l0 are the lengths of volume V along
the weld, and longitudinal cracks A take place. If j
is directed along the weld, then lj and l0 are the lengths
of potential volume V directed across the weld, and
transverse cold cracks form. It can be seen from (2)
and (3) that if the sensitivity of material to longitudinal and transverse cold cracking differs insignificantly, i.e. the values of parameters A, B and h for
longitudinal and transverse cracks are approximately
identical, the probability of longitudinal or transverse
cold cracking depends not only on the level of transverse and longitudinal normal stresses, but also on
the values of lj in potential volume V in a corresponding direction. Therefore, it is quite natural that the
longitudinal cold cracks form in HAZ at the transverse
stresses that are much lower than those in the longitudinal direction.
It follows from the above-said that the probability
of cold cracking in different sections with normal j
can be calculated from equation (2) at the known
values of parameters A, B and η, which depend mainly
only on the microstructure and concentration of diffusible hydrogen, as well as on the distribution of
stresses in the joining zone.
Table 1. Chemical composition (wt.%) of base metal and metal deposited by electrodes
Material
Ñ
Si
Mn
Cr
Ñu
V
Al
P
S
14KhG2SAFD steel
0.13
0.57
1.42
0.44
0.39
0.08
0.08
0.019
0.015
ANP-10 electrode
0.09
0.43
1.90
Traces
Traces
0.01
--
0.020
0.020
12/2009
3
Figure 4. Microsection of cross-section of the weld after the root
pass in the investigated sample at L = 50 mm and T0 = 11 °C
Figure 3. CCT diagram of austenite transformation in steel
14KhG2SAFD
[3], below we give the main calculation results used
to determine parameters of the cold cracking model
(2) in welding heating of the considered steel.
The data on distribution of martensite in cross-section of the root weld (at distance from its beginning
and end) during welding are given in Figure 5. Since
the martensitic-bainitic structure (see Figure 3) is generally formed at a cooling rate ranging from 600 to
500 °C, w6/5 > 7.8 °C/s, the data shown in Figure 5
provide sufficiently comprehensive characterization of
microstructure of the volume (see Figure 4) where a
cold crack is formed, depending on the hydrogen con-
tent and stresses. In particular, as follows from Figure 5, at T0 = 11 °C, which corresponds to w6/5 ≈
≈ 25--35 °C/s in the CCT diagram (see Figure 3), the
content of martensite in the HAZ metal is VM = 0.70-0.90; VM = 0.70--0.40 at T0 = 70 °C; VM = 0.65--0.35
at T0 = 90 °C, and VM = 0.50--0.20 at T0 = 120 °C,
which corresponds to w6/5 ≈ 10 °C/s.
As to the zone of potential cracking proper (see
Figure 4), the martensite content is VM = 0.89, 0.72,
0.65 and 0.50, according to the data of Figure 5. This
corresponds to classical conditions of cold cracking,
other necessary conditions on hydrogen and stresses
being in place.
Figure 6 gives an idea of diffusible hydrogen distribution up to a time moment (t ≈ 200 s) when temperature conditions for cold cracking are created.
These data were obtained for initial hydrogen content
Hfiller = 10 cm3/100 g in filler metal.
It can be seen that the real diffusible hydrogen
content in a crack region (see Figure 4) is not higher
than (3.5 ± 0.5) cm3/100 g. i.e. 35 % Hfiller, by the
moment of crack formation, and that it hardly depends
Figure 5. Printout of calculated values of VM in cross-section of the root weld at L = 50 mm and T0 = 11 (a), 70 (b), 90 (c) and 120
(d): 1 ---- FZ boundary; 2 ---- HAZ boundary; 3 ---- boundary where VM ≥ 0.5
4
12/2009
Figure 7. Printout of calculated values of σ1 (a) and σyy (b) at
T0 = 11 °C and L = 50 mm (Nos. 1--4, Table 2): 1--3 ---- see Figure 5
Figure 6. Distribution of diffusible hydrogen in section z = const
at time momen t = 195 s after a source has passed the given section
at T0 = 11 (a), 70 (b) and 120 (c) °C
on the T0 values in the considered limits. Therefore,
without the data on the stressed state it is difficult to
explain experimental data on the probability of cold
cracking given in Table 2 from the content of quench
microstructures (martensite, see Table 2) and initial hydrogen content Hfiller = 7.0--8.6 cm3/100 g (Figure 6),
which must decrease approximately to (2.5 ± 0.3)
cm3/100 g compared with the calculated one.
The calculation data on residual principal maximum stresses σ1 and transverse normal stresses σyy,
which are responsible for initiation and distribution
of cold cracks of the type shown in Figure 4 for the
variant given in Table 2, are shown in Figures 7--9.
Processing of these data according (1) for HAZ at
VM > 0.5 (in Figures 7--9 this zone is limited by curve
3) allowed
determining the dependence of parameters
__
A, B and η on the hydrogen content in filler metal,
12/2009
Hfiller (Figure 10). It is characteristic that the
A(Hfiller) value is in good correlation with σcr(Hfiller)
obtained in the «Implant» tests at a cooling rate corresponding to a martensite content above 50 % (VM >
> 0.5).
Therefore, it can be concluded from the above-said
that quantitative characteristics of the conditions necessary for cold cracking in welding of low-alloy highstrength steels show up clearly enough by using the
Weibull probability model of brittle fracture. The distribution parameters are a general form of function of
Table 2. Variants of cold crack tests
Variant
No.
Hfiller,
2L, mm T0, °C
cm3/100 g
Number
of
Fracture
samples probability
without
cracks
VÌ
1
100
11
4.0
10
0
0.89
2
100
11
6.0
5
0.5
0.89
3
100
11
7.0
0
1.0
0.89
4
100
11
8.6
0
1.0
0.89
5
140
11
8.6
4
0.6
0.89
6
200
11
8.6
9
0.1
0.89
7
100
70
8.6
2
0.8
0.72
8
100
90
8.6
--
--
0.65
9
100
120
8.6
10
0
0.50
5
Figure 8. Influence of T0 on stresses σyy at L = 50 mm: a ---- T0 =
= 70; b ---- 90; c ---- 120 °C
Figure 9. Influence of L on stresses σyy at T0 = 11 °C: a ---- L = 70; b ---- 100 mm
the content of diffusible hydrogen and microstructural
state of a material in fracture formation.
In fusion welding of 14KhG2SAFD steel, the
Weibull distribution parameters can be taken as__η =
= 4, A(Hfiller) ≈ σcr(Hfiller) (Figure 10) and Bj ≈
≈ 100 MPa⋅mm3/4 at a martensite content in HAZ
equal to more than 50 % (VM = 0.5). The A(Hfiller)
value, like σcr(Hfiller), noticeably increases at lower
VM values in the «Implant» tests, the probability of
cold cracking dramatically decreasing in this steel.
Figure 10. Influence of content of diffusible hydrogen in filler
metal on Weibull parameters A and B at η = 4
6
1. (1998) Welding Handbook: Materials and Applications.
Vol. 4, Pt 2. Miami, USA.
2. Makhnenko, V.I ., Korolyova, T.V., Lavrinets, I.G. (2002)
Effect of microstructural transformations on redistribution of
hydrogen in fusion welding of structural steels. The Paton
Welding J., 2, 6--13.
3. (1967) Thermophysical properties of steels and alloys used
in power engineering: Refer. Book. Ed. by B.E. Nejmark.
Moscow: Energiya.
12/2009
INVESTIGATION OF JOINTS OF TITANIUM ALUMINIDE
WITH TITANIUM ALLOY VT8
PRODUCED BY DIFFUSION WELDING
V.F. GORBAN, G.K. KHARCHENKO, Yu.V. FALCHENKO and L.V. PETRUSHINETS
E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
The welded joints γ-TiAl (Ti--48 at.% Al) with alloy VT8 produced by diffusion welding in vacuum using nanolayered
interlayers of Ti--Al system were investigated. The analysis of strength properties of a joint was carried out using
microindention in the device «Micron-gamma» and also by mechanical shear tests. It was established that after diffusion
welding in vacuum the initial nanolayered layer is transformed into intermetallic being in the state close to nanocrystalline
one.
K e y w o r d s : diffusion welding, titanium aluminide, joint
zone, nanolayered interlayer, microindention, hardness
In the last years the new heat-resistant materials based
on intermetallics, including titanium aluminides, have
been actively developed. These alloys have higher temperatures of melting, elasticity modulus and lower density than superalloys, based on titanium, iron and nickel.
Owing to high aluminium content they do not require
protection against oxidation in the air and in the products
of fuel combustion [1], which allows these alloys to be
efficiently applied as materials for the parts of gas-turbine engines, lining of aircrafts, parts of load-carrying
structures of items of aerospace engineering, and also in
different branches of industry [2].
The aim of work was the investigation of titanium
aluminide alloy (Ti--47Al--1.5Cr--2Nb) with twophase structure (α2 + γ), where α2-Ti3Al and γ-TiAl,
and alloy VT8 (6.5Al--3.3Mo--0.35Si). The diffusion
welding in vacuum (DWV) was performed in the installation U-394 applying nanolayered interlayers
Al/Ti (Ti--52Al) according to the method described
in the work [3] at the optimal conditions: welding
temperature is 1200 °C; welding time is 20 min; pressure is 10 MPa. The electron beam heater was used
as a source of specimens heating.
The application of nanolayered interlayers (NI) in
DWV allows obtaining the composition and structure
in the joint zone close to those of base metal owing
to proceeding of exothermal reaction of self-spreading
high-temperature synthesis. However, the direct precipitation of nanolayers on surfaces being welded is
not always technologically performable, therefore
more prospective is the application of separate NI in
the form of a foil.
At the E.O. Paton Electric Welding Institute the
method of producing similar materials using combined
electron beam evaporation of elements from two
sources in vacuum chamber was developed [4].
Figure 1 shows typical microstructure of cross section of foil specimen in initial state. It is seen from
the Figure that foil consists of continuous relatively
equal layers. Light fringes correspond to the layers of
titanium, dark ones ---- to aluminium.
According to the work [4] during heating of Al/Ti
NI the processes occur in them, resulting in the formation of structure composed of mixture of intermetallics TiAl and Ti3Al. Thus the conclusion can be made
that use in DWV of γ-TiAl NI with titanium alloy
VT8 will allow obtaining the structure similar to that
of base metal.
The analysis of microstructure of bimetal welded
joint of titanium aluminide with titanium alloy VT8
was carried out using microscopes JSM-840 and «Neophot-32». In the joint zone there are no defects in the
form of pores and cracks. At the former boundary of
NI contact with titanium aluminide the common grains
are formed (Figure 2).
The mechanical properties of a joint were determined using microindention which allowed investigating the hard-to-deform alloys without fracture. The
given method in correspondence with the standard
ISO 14577-1--2002(E) allows determining such characteristics of materials as hardness HIT, Young modulus EIT, creep CIT and elasticity ηIT, and also identifying
Figure 1. Typical microstructure of cross section of foil specimen
Al/Ti in initial state [4]
© V.F. GORBAN, G.K. KHARCHENKO, Yu.V. FALCHENKO and L.V. PETRUSHINETS, 2009
12/2009
7
indenting diagram and characteristics of deformation
and stress of material (calibrating dependence of indention):
ÍIT/Å* = K(hs/hñ),
(1)
*
Figure 2. Microstructure (×400) of the joint TiAl + NI + VT8
its structural state according to the hardness relation
towards effective modulus of elasticity. The meanings
of mentioned values are obtained directly from the
curves of automatic recording of kinetic diagram of
load--depth of indenter deepening P--h (Figure 3).
This method is based on fundamental equation of
indention [5], setting the relation between values of
Figure 3. Kinetic diagram P--h (a) and scheme of interaction of
indenter with material (b) [5]: h ---- residual depth of deepening after
removal of indenter; hmax ---- maximum depth of deepening at Pmax
8
where E is the effective modulus of elasticity; K is
the constant of indenter shape; hs, hc are the contact
and out-of-contact depth of indenter deepening.
The value hc is the depth of indenter deepening,
at which the contact between indenter and material
after complete maximum loading Pmax is performed.
In this part of print the elastic-plastic deformation
(possible fracture of material), and also elastic deformation of indenter occur. The part of depth of indenter
deepening, at which the contact with material is absent in result of a dent formed in material around the
indenter, is indicated as hs. In that part of a print the
complete elastic deformation of material takes place.
One of the important features of material is the
relation of its hardness to the modulus of normal elasticity H/E. It is known that H/E value characterizes
the capability of material to resist the changes in sizes
and shape in the process of deformation, it reflects
the conception about the ratio of their elasticity based
on the standard mechanical tests of materials [6].
The H/E* value is a standard hardness, according
to the value of which the structural state of material
can be defined [6]. For coarse-crystalline materials the
mentioned ratio does not exceed 0.03. The fine-crystalline materials (up to 2--5 µm) have a ratio reaching 0.05.
For the metals in nanocrystalline state this ratio is 0.06-0.10. At its value of more than 0.12 the materials are
in amorphous and amorphous-crystalline state.
Microindention was carried out in the installation
«Micron-gamma» at the room temperature using Berkovich diamond pyramid with automatically performed loading (P = 2 N) and unloading during 30 s,
and also with recording of diagrams of loading, holding and unloading in the coordinates P--h. The loading
and unloading were performed using electromagnetic
effect on indenter. The precision of defining the loading P was 1⋅10--3 N, and the depth of indenter deepening h was ±2.5 nm. The values of characteristics P,
hmax, hf, hc, H, E*, E were determined and fixed auto-
*
Figure 4. Relation between values of H/E and hs/hc in materials
with different structural state
12/2009
Mechanical characteristics of welded joint zones obtained according to the data of automatic indention
Area under investigation
ηIT, %
H/E*
εel, %
σel, MPa
1.07
31.8
0.0399
0.124
1181
1.00
32.0
0.0434
0.135
1503
120
0.70
35.8
0.0565
0.176
1964
60
1.40
48.2
0.0710
2.192
1218
HIT, GPa
EIT, GPa
ÑIT, %
Alloy VT8
3.85
101
Intermetallic TiAl
4.90
120
Welding zone
6.40
Initial nanolayered foil Ti/Al
4.20
Note. εel, σel are, respectively, elastic deformation and stress of material under indenter.
Figure 5. Grips for mechanical shear tests of welded specimens:
1 ---- clamping jaws; 2 ---- welded specimens; 3 ---- limiting pipe
matically using corresponding formulae according to
the standard ISO 14577-1--2002(E).
The results of indention of different zones of a
welded joint are given in the Table.
For the materials being joined the structure of a
grain of the size on the level of tens of micrometers and
strength in the elastic zone of about 1100--1500 MPa is
typical. The ratio H/E* for the material of NI in the
initial state (see the Table) reaches 0.0710 that corresponds to nanostructured materials (Figure 4). In spite
of high values of hardness (HIT = 4.2 GPa) the given
material is characterized by a significant ductility CIT =
= 1.4 %, i.e. high values of stress relaxation are typical
of it as compared with materials being joined, thus improving the contact between them.
The influences of welding temperature and high
pressure resulted in significant changes in a transition
layer. Its hardness and elasticity modulus increased
up to the values characteristic of the alloy on TiAl
base. Thus, it was established that after DWV the
initial NI is transformed into TiAl being in the state
close to nanocrystalline one (see the Table).
Authors of the work [7] state that with decrease
in size of structural elements down to nanosize the
life of material is sharply increased. In the works [8,
9] it is also indicated that materials being in nanocrystalline state are characterized by increased mechanical
properties: tensile strength, microhardness, Young
modulus are increased. The authors point out the absence of dislocations in nanometrical crystals, and also
the presence of a large volume of intercrystalline phase
with atomic disorder which results in growth of tensile
strength by 2--2.5 times.
From abovementioned it can be concluded that due
to nanocrystalline state the values of mechanical properties of the zone of joint VT8 with TiAl are at the
high level.
To evaluate the mechanical properties of welded
joints VT8 with TiAl, shear tests were carried out.
The specimens were cut in electric erosion installation
and brought to the size of 95 × 54 mm on the diamond
disc, and then they were subjected to rupture using
special grips (Figure 5).
12/2009
Figure 6. Fractographic pattern of fracture of welded joint VT8 +
TiAl
The fracture of specimens was performed at shear
strength σsh = 6000--6500 MPa which corresponds to
the strength of base metal. The fracture had a toughbrittle character (Figure 6). The analysis of chemical
composition of fracture surface did not reveal the presence of niobium. Thus, it can be assumed that the
fracture was on the side of alloy VT8.
Thus, the investigation of joint zone using microindention allowed determining the fact that in the process of thermodeformational cycle of welding the NI is
transformed into intermetallic with standard hardness
H/E* = 0.0565, characteristic of nanocrystalline materials. The use of TiAl NI in DWV allows producing
welded joints TiAl + NI + VT8 with shear strength
at the level of strength of base metal.
1. Povarova, K.B., Bannykh, O.A. (1999) Principles of development of structural alloys on the base of intermetallics. Pt
1. Materialovedenie, 2, 27--33.
2. Bochvar, G.A., Salenkov, V.S. (2004) Study of alloy on the
base of titanium aluminide with orthorhombic structure.
Tekhnologiya Lyog. Splavov, 4, 44--46.
3. Ustinov, A.I., Falchenko, Yu.V., Ishchenko, A.Ya. et al.
(2009) Producing permanent joints of γ-TiAl based alloys
using nanolayered Ti/Al interlayer by vacuum diffusion
welding. The Paton Welding J., 1, 12--15.
4. Ustinov, A.I., Olikhovskaya, L.A., Melnichenko, T.V. et al.
(2008) Solid-phase reactions in heating of multilayer Al/Ti
foils produced by electron beam deposition method. Advances in Electrometallurgy, 2, 19--26.
5. Firstov, S.A., Gorban, V.F., Pechkovsky, E.P. et al. (2007)
Indentation equation. Dopovidi NAN Ukrainy, 12, 100--106.
6. Firstov, S.A., Gorban, V.F., Pechkovsky, E.P. et al. (2007)
Relation between strength characteristics of materials and
automatic indentation indexes. Materialovedenie, 11, 26--31.
7. Melnikov, S.V., Panteleev, I.A. (2003) Near-surface layers
of structural elements of nanocomposites as an important
structural level of deformation. Matematich. Modelirovanie
Sistem i Protsessov, 11, 67--75.
8. Zolotukhin, I.V. (1998) Nanocrystalline metallic materials.
Sorosovsky Obrazovat. Zhurnal, 1, 103--106.
9. Stepanov, E.I., Grigoriev, M.V., Kirko, V.I. (2008) Effect
of ultradispersed Al2O3 additives on physical-mechanical
properties of corundum ceramics. J. of Siberian Federal
University. Eng. & Techn., 1, 162--167.
9
PRESSURE WELDING OF TITANIUM ALUMINIDE
TO OTHER TITANIUM ALLOYS
V.K. SABOKAR, S.V. AKHONIN, I.K. PETRICHENKO and A.V. YASINSKY
E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
The paper considers metallographic evaluation of the quality of pressure welded joints between intermetallic alloy
Ti--32Al--2Cr and structural alloys VT1-0 and VT6. It is shown that pressure welding provides conditions required for
producing defect-free welded joints.
K e y w o r d s : pressure welding, titanium aluminide, titanium, microstructure, joints, microhardness
Current service conditions of machines and mechanisms require development of new structural materials, possessing high specific strength and resistance
to heavy loads.
As proved by earlier investigations, titanium alloys
of the Ti--Al--Cr system are characterised by low ductility in the cast state at normal temperature, which
substantially limits their application in real products
[1]. To improve the set of physical-mechanical properties at room temperature and provide high heat resistance and thermal stability of such alloys, it is necessary to optimise their chemical composition, develop
Figure 1. Microstructure of contact zones in welded joints of titanium aluminide to commercial titanium VT1-0 (a ---- ×100) and
alloy VT6 (b ---- ×200)
hot deformation parameters, and investigate their
structure and mechanical properties in the cast and
deformed states.
In this connection, determination of principles of
variations in physical-mechanical properties of alloys
of the Ti--Al--Cr system at operational temperatures
of 20--700 °C and evaluation of the effect of structure
and mechanisms of fracture of these materials are topical research and applied problems [2].
Technological experiments and examination were
conducted to investigate structures of pressure welded
joints between titanium aluminide and titanium alloys
of different compositions. The purpose of this study
was to carry out a series of investigations to find out
peculiarities of structural changes, as well as the effect
exerted on them by technological factors.
30 mm diameter rods of alloys VT1-0 (commercial
titanium) and VT6 (Ti--6Al--4V) were used to produce
welded joints on titanium aluminide Ti--32Al--2Cr.
The baseline technology for production of dissimilar
welded joints on the above metals was optimized, and
processes occurring in the joining zone under the effect
of pressure welding parameters were studied in the
course of experiments.
In pressure welding of titanium aluminide, the
joints are made at temperatures below the (α + γ)
transition temperature. This prevents changes in structure of the material and eliminates phenomena caused
by rapid cooling of a joint from high temperatures
(above the (α + γ) transition), which are characteristic
of the majority of other joining methods (fusion welding in particular).
VT1-0 and VT6 samples 23 mm in diameter and
29 mm long, and titanium aluminide samples of the
same diameter and 16 mm long were prepared for
welding. Welding was performed in a process fixture
with free deformation of ductile metal within 5--8 mm
from the joint surface.
Welding of titanium aluminide to the above titanium alloys was carried out in a vacuum chamber of
unit U-874 at a temperature of 820--830 °C. The samples were heated to this temperature, and held for
15 min to level the temperature over the entire section
of the process fixture. Then a pressure of 300 MPa
was applied to them for 10 min. The samples were
© V.K. SABOKAR, S.V. AKHONIN, I.K. PETRICHENKO and A.V. YASINSKY, 2009
10
12/2009
Figure 4. Microstructure (×1250) of diffusion zone with grainboundary diffusion of aluminium to titanium
Figure 2. Microstructure (×1250) of diffusion zone in titanium
aluminide + VT1-0 welded joint
cooled to 200--300 °C in the vacuum chamber. Heating
of the samples in the unit was provided by a molybdenum heater at a rate of about 20 °C/min.
Microstructure of contact zone in the resulting
welded joints of titanium aluminide to commercial
titanium VT1-0 and alloy VT6 is shown in Figure 1.
The contact zones of both joints have a clearly defined
interface between the metals and are free from defects.
Examination of the titanium aluminide + VT1-0
joints in the as-welded state (Figure 1, a) revealed
no common grains (at given welding parameters) in
contact zones of the mating surfaces. The presence of
the diffusion zone both on the side of titanium and
on the side of titanium aluminide can be clearly seen
at high magnification (Figure 2).
X-ray microanalysis showed that the lighter phase
(position 1, Figure 2) in intermetallic alloy had the
following chemical composition, wt.%: 78.9 Ti, 18.88
Al, 2.16 Cr (Figure 3), while grains of the darker
phase containing decomposition products (position 2,
Figure 2) had the following composition: 74.82 Ti,
18.63 Al, 6.55 Cr. These data are indicative of a complex internal structure, in particular, of a presence of
fine inclusions of the β-phase formed as a result of
increase of the chromium content.
Interaction of titanium aluminide with commercial
titanium VT1-0 under the effect of welding parameters
is characterised by diffusion of aluminium through the
contact zone from titanium aluminide to titanium by
the mechanism of grain-boundary diffusion to form a
phase. This process occurs most intensively on the side
of grains containing decomposition products (Figure 3).
Both aluminium and chromium diffuse to titanium,
although chromium diffuses at a much lower rate,
during welding on the side of the light phase of titanium aluminide (Figure 4).
Examination of distribution of microhardness in a
direction normal to the contact zone of the titanium
aluminide + VT1-0 joint (Figure 5) showed the presence of a diffusion zone 5--7 µm wide in a direction
to titanium. X-ray microanalysis revealed occurrence
of diffusion of mostly aluminium on the side of titanium aluminide (see Figure 3, a) and aluminium and
chromium on the side of the phase with decomposition
products (Figure 3, b).
Examinations of structure of the titanium aluminide + VT6 welded joint (Figure 6) showed no
Figure 5. Distribution of microhardness in contact zone of titanium
aluminide + VT1-0 welded joint: l ---- distance between indentations
Figure 3. Distribution of aluminium and chromium in contact zone
of titanium aluminide + VT1-0 welded joint: a ---- light grains;
b ---- grains with decomposition products
12/2009
Figure 6. Microstructure (×1250) of diffusion zone in titanium
aluminide + VT6 welded joint
11
Figure 8. Distribution of microhardness in contact zone of titanium
aluminide + VT6 welded joint
Figure 7. Distribution of aluminium, chromium (a), titanium and
vanadium (b) in contact zone of titanium aluminide + VT6 welded
joint
substantial changes in structure of both metals. X-ray
microanalysis determined distribution of alloying elements in contact zone of the titanium aluminide +
VT6 welded joint (Figure 7). According to the X-ray
microanalysis data, width of the diffusion zone from
contact zone in titanium alloy VT6 is 2.5 µm, and in
titanium aluminide ---- 2.0 µm.
Optical microscopy of microstructure of the welding zone (see Figure 6) revealed fine grains of the
α2-phase with 11--15 wt.% Al, which formed along
the contact zone between the two metals in titanium
aluminide. In addition, the diffusion zone contains
1.8--1.4 wt.% Cr and 0.4--1.8 wt.% V, which diffuses
from alloy VT6.
The content of aluminium in the diffusion zone of
alloy VT6 varies from 6.5 to 11.0 wt.%. The diffusion
12
zone is depleted in vanadium (from 2.8 to 1.8 wt.%)
due to its diffusion to titanium aluminide, but is rich
in chromium (from 1.0 to 1.4 wt.%), which diffuses
from titanium aluminide.
Distribution of microhardness across the contact
zone was investigated. The data shown in Figure 8
prove the presence of the diffusion zone both in alloy
VT6 and in titanium aluminide.
Therefore, the defect-free welded joints between
titanium aluminide and titanium alloys VT1-0 and
VT6 were produced by pressure welding. Characteristic peculiarity of interaction of titanium aluminide and titanium VT1-0 under the effect of welding
parameters is diffusion of aluminium through the contact zone by the mechanism of grain-boundary diffusion to form some phase.
Examinations of the titanium aluminide + VT6
welded joint revealed no substantial changes in structure of both metals.
1. Imaev, V.M., Imaev, R.M., Kuznetsov, A.V. et al. (2005)
New approaches to deformation heat treatment of cast intermetallic alloys based on γ-TiAl + α2-Ti3Al. Fizika Metallov i
Metallovedenie, 100(2), 51--62.
2. Dimiduk, D.M. (1999) Gamma titanium aluminides alloys ---- an assessment within the competition of aerospace
structural materials. Mater. Sci. and Eng. A, 263, 281--288.
12/2009
WELDING AND CUTTING 2009
Essen, Germany, 14--19 September 2009
For 21 years the traditional international «Welding and Cutting» Fair,
which is held every four years, has been a peculiar forum of welders of all
over the world, demonstrating new achievements in the field of welding
and related technologies.
Participating in this Fair were 1015 companies from 42 countries, including
five companies from Ukraine and three from Russia. Despite the global
economical crisis, the number of participants, compared with 2005, did not
decrease. 1000 booths were arranged on the Fair site of over 110,000 m2.
The most representative expositions were those of Germany (417 companies),
then of China (137), Italy (122), USA (49), France (38), Great Britain
(33), The Netherlands (20), India (18), Switzerland (15), Turkey (14),
and Austria (10). The rest of 29 countries had the expositions demonstrating
activities of their companies, each having not less than 10 companies. There
were eight cooperative booths at the Fair: Great Britain (4 companies),
Italy (9), China (22), USA (2 separate booths representing 34 companies),
Taiwan (5 companies), France (11), Japan (4), and Ukraine (5).
More than 60,000 visitors from 128 countries were registered during 6
working days of the Fair. Conference «Mathematical Modelling of Stresses
and Strains in Welded Joints» was held during the Fair.
The Ukraine cooperative booth exhibited developments of the E.O. Paton
Electric Welding Institute of the NAS of Ukraine (Kiev), Open Joint Stock
Company «Kakhovka Plant for Electric Welding Equipment», companies
SELMA (Simferopol), «Zavod Donmet» Ltd. (Kramatorsk), and «Promprylad» Ltd. (Kiev).
The review below includes impressions of the specialists ---- members of the
delegation from the E.O. Paton Electric Welding Institute, showing the
trends in advancement of their respective areas of the welding industry.
The review was prepared by Prof. S.I. Kuchuk-Yatsenko (flash butt welding), Prof. A.Ya. Ishchenko and Prof. L.D. Dobrushin (solid-state joining),
Prof. S.V. Akhonin (welding of titanium), Dr. V.A. Lebedev (equipment
for mechanised arc welding), Dr. A.A. Rybakov (technology, equipment
and consumables for welded pipe production), Dr. A.P. Zhudra (surfacing
materials and technologies), Dr. V.D. Shelyagin (laser welding, laser and
hybrid technologies), Dr. Yu.V. Demchenko (severing, machine tools, postweld treatment), Dr. P.P. Protsenko (welding simulators), and Eng. D.V.
Kovalenko (new capabilities of TIG welding).
Equipment for mechanised arc welding. As to the
amount of exhibits, the equipment for mechanised arc
welding and surfacing looked traditionally the leading
one. Widely presented was the equipment not only of
the known firms and companies from the developed
countries, but also of new companies from China, Portugal etc. Almost all basic arc processes and technologies implemented by using welding semi-automatic
devices are well-known, but there were also some interesting designs solutions, which can be conditionally
12/2009
regarded as the new ones, as they demonstrate modifications of the known developments. A number of
companies exhibited components for semi-automatic
devices: hose packs, feed mechanisms (ready for any
motor to be built into the developed configuration of
mechanism).
Arc welding power supplies (mains and inverter).
Many companies participating in the Fair exhibited
such power supplies: LINCOLN ELECTRIC, KEMPPI, FRONIUS, GRC Evans, Castolin Eutectic,
13
ESAB, CLOOS, CEA, STARWELD, SINCODA,
TELWIN, FIMER S.p.A., FCW International,
KHAZAR-TRAnsfo, and Alpha Laser. The Chinese
industry was represented by companies: HULONG,
HUGONG Welder, AOTAI, Mitec, WTL, UNIPOW,
YDULI, VIGEX, KINF, KAIERDA, JING GONG,
JASIC, etc.
CNC inverter supplies made up the absolute majority of power supplies for semi-automatic welding
devices. Main control algorithms are related to program control via electrode metal transfer, as well as
implementation of synergic control. This is the so
called «cold process» (CLOOS), and SST-process
(LINCOLN ELECTRIC), and a number of processes
on their base with modified pulse parameters. For
example, FRONIUS substantially advanced the CMT
process by timing the welding current pulse source
and pulse feed mechanism following a certain algorithm, thus achieving additional technological effects.
Computerised welding current sources have, as a
rule, from 24 to 60 programs for implementation of
the pulsed arc welding process, depending upon the
process parameters, wire type, weld position etc.
Moreover, exhibited were the sources, e.g. of TELWIN (Italy), with a possibility of on-line programming using the data display.
Most companies produce inverter sources for a current of up to 350 A, but there are also models designed
for currents of up to 600 and 1000 A.
It should be noted that rather simple welding current sources exhibited at the Fair were claimed to be
reliable and requiring no special maintenance.
Electrode wire feed systems. The main product
line includes traditional pairs of feed and pressure
rollers (one and two pairs) with different configurations of grooves and other means for increasing the
pulling force in a feed mechanism of the push type.
However, there are feed systems of the pull type with
a mechanism located in the hose pack holder. In these
systems both geared mechanisms and mechanisms
based on planetary rollers can be used as such a mechanism.
Electric drive packages with DC motors (commutator and commutatorless) are used as an electric
drive. For pulsed feed, CLOOS and FRONIUS use
special designs of step motor drives. Controllers of
the electric drives are mostly of the transistor type,
having a programmed control with feedback systems.
Novelty in this area is fitting the semi-automatic welding station with two independent feed mechanisms
with two hose packs, which are mounted on a common
structure with a common control system and welding
current source. In this case, one feed system is intended
for welding of steels, and the other ---- for welding of
non-ferrous metals. Such semi-automatic devices find
application in motor car construction, where the car
structures also comprise assemblies and components
of aluminium alloys and copper, in addition to steel
elements. These semi-automatic devices are also efficient for welding of long-length structures.
14
Designs of semi-automatic devices. Many semiautomatic devices, mostly of general application, for
welding of steels and aluminium in inert atmosphere
were exhibited at the Fair. Utilisation of multi-component mixtures is insignificant. Few companies, including the known Castolin Eutectic, use flux-cored
electrode wires in semi-automatic devices. Of interest
are also semi-automatic devices based on several work
algorithms, for example, pulse control of electrode
metal transfer and mode modulation. Single-block designs and designs with portable feed mechanisms were
demonstrated. In this case, control and regulation of
the welding process are concentrated in one place.
Semi-automatic device casings made from plastics are
widely applied. A number of companies are ready to
develop and manufacture at a customer request any
casing parts (special cases, reels, fasteners, etc.) for
mechanised equipment.
No mechanised equipment for underwater welding
and cutting, semi-automatic devices using increaseddiameter electrode wires (flux-cored and from aluminium alloys, with diameters of about 3.0 mm or
more), semi-automatic devices with controlled pulsed
feed, based on commutatorless motors, and a number
of others were presented at the Fair.
Such leading companies as LINCOLN ELECTRIC,
ESAB, Air Liquide Welding, Castolin Eutectic, A&N
Europe, Weber SHELD, FRONIUS and a number of
Chinese companies demonstrated in operation, on assemblies and components characteristic of metal structures, the advantages of stationary automated modular
systems and units for making butt and fillet joints,
planar and cylindrical metal structures with straightlined and curvilinear surfaces, as well as for surfacing.
Different samples of such equipment are intended for
implementation of the technologies of welding using
solid or flux-cored wire, in shielding gas atmosphere
and by the submerged-arc method, using self-shielding
wire, or tungsten electrode with filler wire. The systems are made of unified functional modules and include a process module, process tool manipulator, control module, adaptation module, and environment protection module. These systems are based on advanced
designs of drives, actuating mechanisms, specialised
fixture and environment comfort ensuring systems.
They can be taken as a basis for development of the
equipment to realise welding and surfacing technologies by small and medium business firms: surfacing of
railway and crane wheels, shafts, rollers and augers,
welding of tanks, cylinders, ladles, flat metal structures of lighting supports, welding of elements and
necks to tanks, etc.
Of high interest among visitors were versatile
light-weight carriages (made mostly by ESAB,
FRONIUS and some Chinese companies). They are
intended for displacement of gas-oxygen cutters and
torches in any spatial positions, and can be successfully used in field and under stationary conditions for
cutting, welding, surfacing of straight-lined and curvilinear surfaces, as well as annular pieces. Weight-
12/2009
dimension and technical characteristics of these products are such that they can be moved on guide rails,
flexible strips, or without them. Undoubtedly, they
can be widely applied for automation of welding, surfacing and cutting processes under factory conditions
at small business firms and workshops.
New capabilities of TIG welding. Characteristic
feature of this Fair is that not only the world leading
companies, such as LINCOLN ELECTRIC, ESAB,
FRONIUS, EWM and ITB, but many others, including small and little-known ones, pay much more attention to development of equipment, consumables
and accessories for TIG welding. The obvious focus
at previous exhibitions was on MIG/MAG welding,
out of other arc welding methods. The following can
be marked out among a wide variety of presented
developments and equipment.
Technische Universitaet Chemnitz (Germany) presented a device providing an increased penetration
depth in TIG welding. The principle of its operation
consists in the pulsed feed of a shielding gas (argon)
at a certain frequency (5 Hz), the argon flow rate in
pulse being 30 l/min, and that in pause ---- 5 l/min.
Samples of butt joints on stainless steel 5 mm thick,
welded in one pass without groove preparation, were
demonstrated. VBC Group (Great Britain) exhibited
new power supply InterPulse, which provides contraction of the arc with decrease in HAZ, reduction
of heat input by a factor of 1/3, compared with traditional TIG welding, possibility of welding a new
generation of single-crystal superalloys, and welding
of titanium alloys using no protective chambers and
spouts.
Jetline Engineering (USA) and United ProArc
(Taiwan) offer a wide range of units for TIG welding
of longitudinal and circumferential welds, including
simple and inexpensive ones. WELMAX (Norway),
having a wide experience in field welding of pipes at
oil deposits, presented automated units for roll and
position butt TIG welding, including narrow-groove
TIG welding, by using a heated filler wire.
Astral Engineering (Germany) demonstrated integrated equipment lines for spiral seam welding of hot
rolled steel pipes of different standard sizes, with diameters ranging from 170 to 3050 mm, thickness ---from 4 to 25.4 mm, and length ---- from 6 to 20 m.
Systec Elektronic und Software (Germany) presented the integration-ready positioning systems
DriveSets for translational and rotational movements.
These are complete versatile mechanotronic systems,
which are delivered in a fully assembled state and
include not only kinematics and control devices, but
also software and documents. Their key advantages
are as follows: a wide range of technical parameters
(load, speed and grade of accuracy), over 36,000 modifications, simple on-line selection by a diagram, and
delivery term of 3 to 5 weeks.
About 40 companies presented different types of
equipment for orbital TIG welding, such as highly
automated and computerised equipment with seam
12/2009
tracking and process visualisation systems manufactured by such German companies as Arc Machines
GmbH, ORBIMATIC and Orbitec GmbH,
POLYSOUDE (France), ESAB AB (Sweden), and
Liburdi Automation Inc. (Canada).
Meta Vision Systems (Great Britain) and SERVOROBOT (Canada), which are the leaders in the field
of laser seam tracking systems, demonstrated a range
of sensors and systems to be applied with different
welding methods (TIG, MIG/MAG, submerged-arc
and laser welding) for manufacture of pipes, tanks,
casing structures, etc., and robotic technologies for
automotive industry and space engineering. Scansonic
(Germany) also exhibited a versatile optical sensor
for seam tracking systems to monitor different welded
joints. CAVITAR (Finland) and BFi OPTILAS (Germany) introduced visitors to an interesting joint development ---- high-speed laser-optical system Cavilux
Welding Monitoring, which allows visual observation
of the entire welding process (both in low- and hightemperature zones) at a very high quality and in real
time. BFi OPTILAS also demonstrated a wide range
of different digital video cameras, displays and software, which can find wide acceptance for research
purposes in the field of various welding processes, as
well as for commercial application.
Ing. Grimm Schweisstechnik (Germany) presented
the high-precision CNC welding head DKS 9000 for
filler wire TIG welding, designed for automated systems and robotic complexes. Wire diameter ranges
from 0.8 to 2.4 mm, and wire feed speed (continuous
and pulsed) is adjustable from 0 to 15 m/min. STB
Schweisstechnik (Germany) demonstrated machine
TIP TIG with a manual welding torch for heated filler
wire TIG welding. Key advantages of this machine
include high productivity (deposition rate ---- up to
2 kg/h, and manual welding speed ---- up to
80 cm/min), and up to 150 % reduction of costs compared with conventional TIG welding. Rohrman
Schweisstechnik (Germany) presented removable nozzle Champagne Nozzle II for manual TIG welding
torches. The main advantages are a large diameter of
the nozzle ---- 28 cm, and a laminar flow of gas at its
increased rate, this allowing a substantial improvement of the protective potential of the nozzle, which
is particularly important for TIG welding of stainless
steels and reactive metals. Moreover, the possibility
exists of considerably increasing the tungsten electrode extension ---- up to 50 mm, which will allow a
welder to better watch the weld pool during welding.
Ges. fuer Wolfram Industrie (Germany) offered
tungsten electrodes of the WIT-STAR and ORBISTAR types, containing no thoria, which is a radioactive element. In addition to improved safety, these
electrodes are characterised by an increased life compared with conventional ones. Several companies presented different devices for sharpening of tungsten
electrodes: small-size versatile tools of the Trix series,
as well as tool Neutrix, which is delivered in a case
(total weight in a set ---- 2.8 kg, power ---- 650 W).
15
Aquasol (USA) offered the following range of materials increasing the efficiency of welding: Aquasol ---- water-soluble paper and strip, EZ Purge ---ready-made self-adhesive plugs of water-soluble paper
for gas purging, Solugap ---- water-soluble gaskets of
a unique design for bell-and-spigot welding,
Fiback ---- fibreglass gasket strip for elimination or
reduction of the need for gas purging and ensuring of
back shielding of the weld pool, EZ Zone ---- two-layer
aluminium strip for sealing the joint gaps, LiquiFilm ---- water-soluble polymeric film to be used as a
barrier for purging gas, and EZ Wipes ---- multi-purpose wiping napkins. The Company demonstrated a
portable self-contained oxymeter OX-100 with a resolution of --0.1 % (1000 %) for precise measurement of
oxygen concentration after purging the pipes with
shielding gas (argon).
NITTY-GRITTY S.R.L. (Italy), Chemetall AG
(Germany) and other companies presented different
devices of the Clinox and Antox types for cleaning
the welds after welding.
Welding technology, equipment and consumables for pipe production. Technology and equipment for production of large-diameter pipes were exhibited at the Uhrhan-Schwill and ESAB booths. In
contrast to the 2005 Fair, Uhrhan-Schwill did not
have its own booth and arranged its exposition at the
LINCOLN ELECTRIC booth. Again, unlike the previous Fair, only the four-arc device for welding the
internal welds in pipes, a full analogue of the 2004
device, was exhibited at the LINCOLN ELECTRIC
booth. The device is equipped with a system of support
and guide rollers, adjustable rod, laser system for
maintaining the electrode extension, digital system
for control of the welding process and other elements.
Such devices were integrated into the equipment supplied by SMS Meer to fit new pipe production shops
at the Vyksunsky Metallurgical, Izhorsky Pipe and
Chelyabinsky Pipe Rolling plants.
It is a known fact that in 2008/2009 UhrhanSchwill offered, e.g. for the Khartsyzsky Plant, a new
design of the apparatus for inside welding using no
support rollers (that does not bear on the internal
surface of a pipe). This design of the apparatus is now
at a stage of optimisation. The five-arc apparatus
manufactured by the Company for outside welding of
pipes was not exhibited at the Fair. According to the
available information, the Company does not have
any new technological solutions for welding of pipes,
and recommends using the submerged four- and fivearc welding processes, similar to the developments of
the E.O. Paton Electric Welding Institute. Inverter
power supply Power Wave 1500 developed by LINCOLN ELECTRIC in collaboration with UhrhanSchwill, which was exhibited at the previous Fair but
is not presented at this Fair, has not yet found an
application in pipe welding production. Europipe
bought a batch of such power supplies four years ago.
However, no information is available as yet concerning
their application and technological advantages.
16
LINCOLN ELECTRIC offers the known agglomerated aluminate-basic fluxes 995L and 998L and wire
of the Fe--Mn--Mo (L-70) and Fe--Mn--Mo--Ti--B
(LNS 140 TB) systems to be used as consumables for
pipe welding production. There are no new developments in the field of consumables for welding of pipes.
A four-arc device for inside welding of pipes was
exhibited at the ESAB booth. This device uses a ramtype flat contact tube arranged across the welding
direction, instead of a sleeve-type one.
In addition, a three-arc apparatus was exhibited
at the ESAB booth. It was used to demonstrate welding of thick-walled (about 60 mm) shells. The process
employed is similar to three-arc welding of pipes.
ESAB, like LINCOLN ELECTRIC, offers the
known aluminate-basic flux of the OK 10.71 and OK
10.74 grades, as well as wires of the same alloying
systems for welding of pipes. According to the results
of investigations conducted by the E.O. Paton Electric
Welding Institute, flux OK 10.71 is unsuitable for
multi-arc welding of pipes, and is not applied at pipe
welding plants of Russia and Ukraine. New developments in the field of consumables for pipe welding
production are not available.
Surfacing. No substantial changes in terms of development of new technologies have occurred during
the last four years in the field of arc surfacing. Traditionally, among the exhibitors were such companies
as Sulzer Metko Woka (Germany), Castolin Eutectic
(Switzerland), WELDING ALLOYS GROUP (Great
Britain), VAUTID GmbH (Germany), EIPA Eiseh
Palmen (Germany), Contex (Germany), DURUM SA
(Germany), ERGOTEM SA (Greece), SV Schweissund Verschleisstechnik GmbH & Co. KG (Germany),
Kalenborn Kalprotect GmbH & Co. KG (Germany),
Beijing Advanced Materials Co., Ltd. (China), and
the Chinese branch of Asiamet Inc. (USA), as well
as a number of smaller companies from different countries.
The majority of these companies presented samples
of deposited parts mostly for metallurgical, mining,
ore-dressing, cement and other industrial sectors. The
dominating place among a wide range of surfacing
technologies is still taken by automatic flux-cored wire
open- and submerged-arc surfacing, while the most
common product among the corresponding ones is still
a wear-resistant bimetal plate. In contrast to the earlier widespread technology for surfacing over a charge
layer, today such major manufacturers in surfacing
operations as Castolin Eutectic, EIPA, Contex, etc.
perform surfacing of plates by the flux-cored wire
open- or submerged-arc methods. VAUTID has up 12
machines in operation, and 10 machines are used round
the clock for surfacing of plates at a German factory
of Castolin in Kriftel.
The scopes of production of bimetal plates clad by
the PTA process, where a steel or nickel-chrome-boron
matrix is reinforced by the spherical or crushed tungsten carbide granules, have substantially grown. DURUM demonstrated a 2 + 2 mm thick plate clad by
12/2009
using the above materials. Sulzer Metco Woka, Castolin (Austrian subsidiary) and a number of other
companies combine the PTA process with laser to deposit composite layers on drilling equipment parts,
such as calibrators, reamers, bits, etc.
Traditionally, almost all the companies presented
a wide range of surfacing consumables, primarily fluxcored wires, electrodes, and, to a lesser degree, sintered strips. Chromium carbide based flux-cored
wires, alloyed with niobium (up to 7 %) and vanadium
(up to 8 %), are offered as an achievement. The metal
deposited with these wires is resistant to intensive
abrasive and gas-abrasive wear at temperatures of up
to 750 °C. Of special interest is a flux-cored wire
produced by Castolin, which provides a nanostructure
with hardness of up to HRC 70 in the deposited layer.
The quantity of companies producing and consuming
tungsten carbides has markedly grown. Sulzer Metco
Woka, DURUM, Technogenia, BAM (China), Asiamet (USA) and Carbide and Metal (C&M) (Germany) offer today several types of hard-facing powders based on tungsten carbide: macrocrystalline WC
with 6 % C, fused WC + W2C, crushed and spherical
(produced by melting of crushed tungsten carbide in
a jet of induction plasma), as well as synthesised cermet alloy of tungsten with 2--6 % Co. It should be
noted that spherical tungsten carbide produced by the
technology of the E.O. Paton Electric Welding Institute, which is based on centrifugal spraying, features
the best properties and is beyond comparison, according to the unanimous conclusion.
Equipment for surfacing and cladding operations
was exhibited at the Fair by an example of a number
of specialised machines and a wide range of robots
offered by different companies.
Specialised machines designed for surfacing and
welding of large-size parts are characterised by a massive modular frame mounted on a strong column or
gantry, this providing a high accuracy of surfacing
and welding operations. An example is a machine offered by Key Plant (Germany). Of special interest
are the WELDING ALLOYS machines for cladding
of cylindrical parts up to 3 t in weight, as a well as
a machine for inside surfacing of casing parts and pipes
up to 3 m long. Some companies presented small modular surfacing units.
Laser equipment, laser and hybrid technologies.
Laser equipment and laser and hybrid technologies
were presented at the Fair by over 15 companies: IPG
Photonics (USA), IPG Laser GmbH (Germany),
ROFIN SINAR, TRUMPF, JENOPTIK, LASERMAK TURKEY, HIGHY AG, Alpha Laser (Germany), Scansonic, WINLaser NC, PEIS-LASER-MATERIAL, BEARBEITUNG, GNLASER (China),
BAM, SLV-Haller (Germany), etc.
Of high interest was exposition of IPG, which
offered new samples of high-power fibre lasers, the
technical and operational characteristics of which are
superior to those of other laser designs:
12/2009
• service life ---- 50,000--100,000 h with a possibility extending it at low costs;
• absence of consumables and minimal operating
costs;
• minimal time for commissioning, preparation of
premises and starting-up;
• possibility of multi-fold increase in power by
adding extra units;
• possibility of transporting the beam via an optical
cable 10--100 m long and switching the beam to 6--8
such cables for arranging multi-functional workshops;
• possibility of operating the equipment by a staff
with primary and secondary technical education.
The IPG single-mode ytterbium fibre lasers with
a power of up to 2 kW have superior beam characteristics. Lasers of the YLR-1000SM and YLR2000SM types feature a beam divergence (BPP) of
0.4 mm⋅mrad in operation from active optic feeder
20 µm in diameter, and 2 mm⋅mrad in operation via
transport feeder 50 µm in diameter.
The 30 kW fibre laser YLS-30000 was demonstrated at the Fair, having a beam quality index of
less than 2 mm⋅mrad at a 5 kW power, this being
several times lower compared with other laser designs.
This laser can be completed with cutting and welding
heads of the HIGHYAG Company, as a well as with
a scanner allowing an extensive deflection of the laser
beam to 160--200 mm at a workpiece to scanner distance of 600 mm.
ROFIN SINAR also demonstrated the single-mode
ytterbium fibre laser with a power of 1 kW and high
beam quality. TRUMPF presented a 4 kW disk laser
(with optical fibre) connected to a three-coordinate
manipulator with a scanner mounted on it, having the
following technical characteristics: focal distance ---450 mm, time of full deflection ---- 30 ms, beam diameter
on a workpiece ---- 600 µm, and sizes of a work volume:
X ---- 206 mm, Y ---- 352 mm, and Z ---- 140 mm. The
technology of connecting two laser beam control systems
makes it possible to substantially increase the productivity of the unit and perform welding «on the run».
Rapid «jump» of the laser beam from one welding point
to the other by means of the scanning optics reduces the
losses of time for movement of the welding head by the
manipulator, and the time is spent only for welding.
Power and quality parameters of disk lasers have been
considerably improved. For example, BPP is 2 mm⋅mrad
at a power of 1 kW, and 8 mm⋅mrad at 2--8 kW. Power
of a single unit increased to 10--16 kW.
Interesting devices, scanners and accessories were
demonstrated by Scansonic and ILV DC-SCANNER.
Samples of the head for hybrid laser-arc welding were
presented by HIGHYAG, FRONIUS, ESAB,
CLOOS, SLV-Halle, etc.
Samples of 900 mm diameter pipe with a wall
thickness of up to 14 mm, welded by the hybrid laser-arc method, were demonstrated by IPG, BAM,
SLV-Halle (video) and VIETZ.
IPG presented samples and leaflets on laser-resistance welding. Equipment for laser, plasma and gas
17
cutting was demonstrated by such companies as ESAB,
MESSER, KARABASIS, HUGONG, Koike, HONEYBEE, Eckert, PROARC, TECHNO, WTL,
Szhuayilong, AUTOREX, etc. Most impressive were
the ESAB, Koike and Eckert machines for oxygen
cutting. The samples made by using these machines
have a smooth surface and minimal inclination of
walls, as well as good surface with a bevel.
Of high interest are 5- and 6-coordinate manipulators and robots performing cutting and welding of
complex-configuration parts, e.g. cutting-in of pipes
at different angles. Undoubtedly, the laser cutting
units are beyond comparison for treatment of thin
metal. LASAG presented a series of units performing
laser cutting and drilling with record-breaking characteristics: cutting of metal 1--0.04 mm thick, and
drilling of metal up to 0.5 mm thick at an angle of
30° with 0.1 mm diameter hole.
Welding of titanium. Traditional technologies for
welding of titanium were presented at the Fair: electron beam welding and TIG welding in argon atmosphere.
The Technology for EBW of titanium is offered
mostly for aircraft engineering and power machine
building. EBW units were presented by such companies as Probeam Systems GmbH (Germany), TECHMETA (France), and Cambridge Vacuum Engineering (Great Britain). All the companies offer an entire
package of services for delivery of the EBW equipment
and technologies. Deliveries of the equipment include
vacuum chambers with dimensions ranging from 300 ×
× 300 × 300 to 7000 × 7000 × 14000 mm, electron
beam guns with accelerating voltage of 60 to 175 kV
and beam power of up to 80 kW, together with power
supplies, automated loading and unloading systems
and manipulators, control systems, vacuum systems
allowing a chamber to be evacuated within less than
30 min, as well as other auxiliary systems. In addition
to welding, the companies offer technical and technological solutions for electron beam surface treatment
and cutting (hole drilling).
It should be noted that Cambridge Vacuum Engineering since 2006 has been active in implementation
of new developments of TWI under licence agreements, offering, in particular, the technology for electron beam surfacing of near net shape billets (near
net shape technology), EBW under low vacuum conditions (reduced pressure EBW), etc.
Technologies for TIG welding of titanium are offered primarily for application in chemical engineering
(welding of heat exchanger tubes to tube plates), the
focus being on the orbital position butt welding process. Units for orbital welding were presented by such
companies as Orbitalum Tools (Germany), Stelin Srl
(Italy), Progettazione Apparecchiature Industriali Srl
(Italy), Arc Machines, Inc. (USA), and
POLYSOUDE (France). All suppliers of such equipment offer integrated deliveries, including specialised
welding heads with 100 % shielding of the welds with
inert gas in welding of 30 to 300 mm diameter pipes,
18
welding arc power sources with computer control of
welding parameters, groove preparation equipment,
auxiliary fixture and devices. In addition, the above
companies provide training of personnel in operation
of the equipment supplied.
For position and roll but welding of pipes with a
wall thickness of up to 150 mm, made from conventional and stainless steels, Arc Machines offers a narrow-gap TIG welding technology and equipment, and
POLYSOUDE ---- narrow-gap MIG welding technology and equipment.
Resistance welding. Equipment for resistance
welding was demonstrated at booths of 15 companies.
Among them, the widest range of the equipment was
exhibited by DALEX Schweissmashinen GmbH (Germany), GF Welding S.p.A. (Italy), Semsa (Italy),
Wantec (Germany), ANTECH ELECT Ltd. (China),
etc. In the most part, the equipment consists of versatile and specialised machines for spot and projection
welding, as well as power supplies for them.
The common trend in the last years for all classes
of this equipment has been the use of inverter power
sources, which provide a three-phase mains supply,
improvement of energy indicators, and wider capabilities of adjustment of welding process parameters.
Over 80 % of all machines for resistance welding
with a power of over 100 kV⋅A, which were exhibited
at the Fair, were equipped with the transducers providing the three-phase mains supply, as well as the
use of the direct current in the welding circuit and
direct current in the secondary welding circuit. It
should be noted that a dramatic reduction in price of
such transducers has occurred within the last three or
four years. This, for sure, promoted their wider application in the up-to-date resistance welding equipment. It should be emphasised that decrease in dimensions and weight of the transducers allowed their extensive utilisation in mobile tongs for spot welding.
Many types of tongs with built-in power supplies (rectifiers, high-frequency transformers) were exhibited.
The second peculiarity of this equipment consists in
using a modular principle of packaging of the tongs
assembled from typical elements (rectifier blocks,
transformers, control systems). This resulted in the
specialised equipment adapted to the maximum possible degree to peculiar designs of weldments, and
allowed using it as part of robotic complexes.
In addition to the spot welding equipment, many
types of portable units for welding of studs of different
sections and configurations were exhibited at several
booths. The units provide welding by the capacitor
energy storage and electric arc discharge methods.
DALEX Schweissmashinen (Germany) presented
at its booth a complete set of inverter power sources
for spot welding, with a power of 100 to 1000 kV⋅A.
In addition to a uniform three-phase supply, the inverters allow substantial decrease in impedance of the
secondary circuit of a welding machine, and increase
in the welding currents owing to the use of the direct
current.
12/2009
Semsa demonstrated at its booth a wide range of
spot welding equipment integrated into high-efficiency production lines, including with robot part
loading. Of interest is an original unit for resistance
seam welding of thin-walled cylindrical shells made
form galvanised steels (with a productivity of up to
2 m/min), as well as for welding of longitudinal
stiffeners.
A set of modules for spot welding, mounted on a
gantry with a possibility of their multi-axis spatial
displacement, was presented. The set of integrated
modules for packaging of specialised tongs for spot
welding was exhibited at the booth of CF Welding.
They include transformers with an intermediate frequency of 1000 Hz, which are most commonly used
in inverters for spot welding.
The stud welding equipment, with a capacitor or
electric arc discharge used for welding, was demonstrated by Nelson, HBS, Soyer, Koco (Germany) and
SILICON (USA).
In the first case, small diameter (2--10 mm) parts
are welded to a thin sheet (0.6--1.0 mm). Advantages
of this technology are minimal distortions, absence of
incipient melting of the reverse side, and possibility
of welding to a thin point, including in dissimilar
materials. Welding of large-diameter (up to 25 mm)
studs is performed by the electric arc discharge technology, which allows welding of threaded studs, anchor bolts and other fasteners. The portable hand tool
makes it at a high productivity (the welding time is
no more than 1 s) by using standard electric arc welding power supplies.
Silicon developed machines for welding of bolts
and anchors up to 50 mm in diameter by using the
inverter power supplies designed for currents of up to
4000 A. In this case, to form the weld it is necessary
to use special preparation of edges of the rod being
welded, as well as special ceramic rings placed in the
welding location. Welding of rods more than 20 mm
in diameter was demonstrated for the first time at the
Fair and aroused visitors’ interest.
Solid-state joining. This joining technology, including explosion welding, friction stir welding and
other related processes, was presented at the Fair by
such companies as DMC (USA), Uhde GmbH (Germany), Van Campen Exploform (The Netherlands),
Druseidt (Germany) and ESAB (Sweden).
American Dynamic Materials Corporation (DMC)
is a world leader in the field of explosion welding and
cutting of metals. Today the Corporation includes
such European companies as Dynaplat (Germany),
Nitro Metall (Sweden) and Nobelclad (France). DMC
covers over 60 % of the world market in production
of large-size bimetal plates by explosion welding.
Uhde is a world leader in manufacture of electrolytic cells for production of caustic soda. The cells use
electrical bimetal adapters, i.e. long Ti + Ni strips
1.0 + 1.0 mm thick, respectively, which are manufactured only by explosion welding. The annual demand
for the Ti + Ni adapters is 240,000 pcs.
12/2009
Van Campen Exploform B.V. is involved mostly
in explosion forming of complex and high-precision
parts from metal plates. The Company is planning to
widen its interests in the field of explosion welding
and make evacuated explosion chambers.
Among the related areas presented at the Fair,
noteworthy are such companies as Druseidt producing
Cu + Al bimetal by cold rolling, Cytec manufacturing
equipment and tools for friction stir welding, and
Orbitalum Tools manufacturing guns for semi-automatic welding of tubes into explosion welded bimetal
tube plates.
ESAB demonstrated friction stir welding of aluminium alloys in different spatial positions by using
a robot and five sets of assembly-welding devices.
Billets of semi-finished products up to 5--6 and 10-20 mm thick were welded with partial and full penetration by the one- and two-pass methods. Butt
straight-lined and curvilinear welds were made on flat
and cylindrical parts. Fillet, edge and T-joints, as
well as curvilinear welds were welded following the
preset program owing to the use of robot and precise,
rigid assembly fixture. The effective welding head
with a work tool is connected via adapter to the drive
spindle and motor. Available is a table of technical
parameters when using a spindle with a rotation speed
of 3000 rpm (force ---- 13 kN, and torque ---- 44 Nm).
Of interest among the other ESAB developments
as applied to aluminium are orbital heads (series of
three standard sizes) for position butt welding of pipelines.
Severing, mobile machine tools and equipment
for mechanisation of welding processes. Severing.
In the cases where traditional gas cutting equipment
is unacceptable, the world practice in the field of
severing, dismantling of structures or grooving of defects on high-alloy and carbon steels, cast iron, aluminium and copper alloys is to use electrodes with
special coverings, which require no oxygen or compressed air to be fed to the cutting zone. Such developments were demonstrated by ESAB, LASTEK, LINCOLN ELECTRIC and other companies. Almost all
electrodes provide a sufficient speed of cutting of such
metals in all spatial positions, they do not overheat
and are fully utilised. In cutting of corrosion-resistant
and low-carbon steels the cut edges are not carbonised,
this allowing avoidance of their subsequent cleaning
before welding.
Mobile machine tools. Machining before and after
welding is a pressing problem when performing comprehensive repairs, for example, of unique cast and
welded structures of metallurgical equipment, mining
equipment, different-application main and industrial
pipelines and power plant equipment by welding and
related technologies. Therefore, mobile equipment for
machining, including for groove preparation, removal
of defective areas, removal of cold-worked layers,
high-frequency treatment of mating locations on structures, or partial dismantling, is in great demand. Such
mobile equipment was presented at the Fair by such
19
companies as PROTEM, COFIM, AXXAIR, PIPEWORK EQUIPMENT, TechnoPipe, TRUMPF, etc.
Among them of interest is the following equipment:
• machine tools designed for treatment of ends of
pipes and shafts with diameters ranging from 27 to
1460 mm. They can be fitted with a pneumatic or
electric drives, depending upon their standard sizes;
• machine tools designed for boring after repair of
stop valves, flanges and mating surfaces. The drives
here are mostly electric;
• boring machine tools with a possibility of being
connected to the inside surfacing equipment. In such
cases surfacing and machining are performed by one
unit. They are characterised by efficient design and
technological solutions for utilisation in restricted volumes, as well as by a wide variety of drives.
All types of the equipment feature rigid load-bearing and articulator connections designed for severe
operational conditions, as well as compact drive systems to achieve an optimal power, weight and dimensions ratios. Assembly is performed by using setup
brackets, spherical bearings and self-aligned cones.
The known methods for postweld treatment of
welded structures, which improve fatigue resistance,
are conditionally subdivided into five groups: mechanical, thermal, deformation, pulse, vibration and
special. Owing to availability of equipment and sufficient efficiency, the deformation methods have received the widest acceptance. They are based on the
use of the mechanical energy introduced in different
ways to induce deformations in different zones of
welded joints. PFEIFER and PITEC offered corresponding specialised equipment and technologies, and
demonstrated the results evidencing an increased fatigue resistance of welded joints provided by peening
the weld metal and near-weld zone with one- and
multi-striker tools. Examples of practical application
are metal structures of off-shore stationary platforms,
mast structures, cranes, bridges, rolling stock, excavating machines etc.
Welding simulators. The exposition of technical
means for practical training of welders was arranged
at the DVS booth. They include welding simulators,
in particular, of eight companies: FRONIUS (Austria), FWBI (Germany), LINCOLN ELECTRIC,
Nave (Hungary), SIMFOR (Spain), SLV (Germany),
123 Certification (Canada), and E.O. Paton Electric
Welding Institute (Ukraine).
The training devices can be subdivided in the
method of simulation of a welding process into two
big groups: electronic (virtual) and low-amperage
(arc). They realise the idea of computer simulation of
movements of a welder in performing practical tasks.
The virtual welding software programs are available,
used to optimise the main motive habits, e.g. at different welding speeds, different electrode tip to workpiece distances, and different electrode inclination angles. The training devices software includes simulation
of welding exercises in different spatial positions, in
butt and fillet welding. The feedback and in-process
20
analysis helps a trainee to faster acquire the motive
habits required to perform manual arc welding.
Special sensors of seam tracking systems, which
trace position of a work tool (electrode holder/torch)
and its movement speed are employed to simulate the
weld shape and welding quality.
Electronic training devices simulate the welding
situation on the monitor screen built into the welder’s
helmet, and/or on the display built into the device
console. Simulator of a structure welded is present
not in all the devices, and serves for initial orientation
of a trainee in virtual reality, as a similar structure is
displayed on the monitor screen. As a rule, ergonomic
indicators of the hand tool simulators are substantially
different from the real hand tools. At the Fair, the
electronic simulators were presented by FRONIUS,
FWB, LINCOLN ELECTRIC, Nave, SIMFOR, and
123 Certification. Electronic simulators can serve as
an additional technical means to fix theoretical information at a level of educational films and animation
cartoons. They give a good idea of key elements of
the welding situation and their interaction. Nevertheless, at present they do not form the psychomotor
(motive) habits of the trainees in performing the welding process, as the main ergonomic peculiarities of
welding are not taken into account. Noteworthy
among the exhibited electronic simulators are the
FRONIUS and LINCOLN ELECTRIC ones, which
have a friendly interface, are convenient in operation
and provide good visualisation of elements of the welding situation (weld, heated metal, pool and arc).
Welding simulators with the technology of a simulated or virtual welding process allow simulation of
movements of a welder during welding by visualising
the welding process and analysing the results.
The virtual welding process and its results are displayed on a special screen built into the welder’s shield
and on a separate monitor. All parameters of the training process are saved and can be further used for detailed analysis by a trainer. The main idea is to simulate the necessary conditions to acquire the psychomotor habits in practical training of welders on the
basis of computer technologies using no real arc welding process. Application of such simulators is meant
to solve the problems of arrangement of training, improve the quality of vocational training, and reduce
the training cost and terms.
It should be noted that the electronic virtual simulators are costly (their price is from 50,000 to 80,000
Euro).
The low-amperage arc welding simulators are
based on simulation of the welding situation by using
the real low-amperage arc. Ergonomic characteristics
of such a model are as close as possible to the real
process. In turn, this makes it possible to use such
simulators at the initial stages of formation of the
psychomotor habits in performing the welding process.
The low-amperage arc simulators were presented
at the Fair by SLV and E.O. Paton Electric Welding
12/2009
Institute. They are similar in their functional capabilities. So, we will dwell on their differences.
The SLV simulator is an original optical method
for defining a spatial position of the hand tool simulator. This is done by using a video camera, as well
as two red light diodes on the hand tool simulator.
The spatial position of an electrode simulator is determined from a relative position of the light diodes
with respect to a fixed position of the video camera.
This method gives good results, but requires additional
soft- and hardware costs, thus leading to a marked
increase in price of the simulator.
Software is well organised, and a touch screen is
used to control the program.
Thickness of a simulator of the mating surfaces
(metal plate about 2 mm thick) and insufficient power
of the electric current source limit the possible length
of the arc gap to 2 mm. The arc is hard to maintain.
As a result, performance of the welding process requires the psychomotor habits. Therefore, it is difficult
to use the simulator at the early stages of training,
but it can justify itself in maintaining the habits required to perform the welding process. The price of
the simulator is from 20,000 Euro, depending upon
the components.
The simulator of the E.O. Paton Electric Welding
Institute (MUATs) uses real work tools (electrode
holders and torches) with built-in position sensors
used as hand tool simulators. This approach allows
preserving the ergonomic characteristics of the hand
tools. The simplified software provides operation of
the simulator controlled by the up-to-date and obsolete computer models without any loss of its functional
capabilities. The price is 1500 Euro.
FEATURES OF LASER-MIG WELDING
OF HIGH-STRENGTH ALUMINIUM ALLOYS
V.D. SHELYAGIN, V.Yu. KHASKIN, V.S. MASHIN, M.P. PASHULYA, A.V. BERNATSKY and A.V. SIORA
E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
The paper deals with the influence of the intensity of evaporation of base metal and electrode wire elements, as well as
shielding gas atmosphere composition on laser radiation propagation to the metal being welded in hybrid welding of
aluminium alloys. Technological features of laser-MIG hybrid welding were studied, modes were selected and the obtained
results were compared with consumable electrode pulsed-arc welding.
K e y w o r d s : laser-arc welding, aluminium alloys, pulsed
arc, consumable electrode, hybrid process, butt joints, mode parameters, characteristic defects, mechanical properties
Aluminium alloys are applied for welded structures
of motor and railway transport, various-purpose ships,
aeronautical and space engineering, instrument casing, etc. The main problem in fabrication of such structures most often is producing sound welded joints,
which are made using filler or electrode wires, as well
as edge flanging. Wall thickness of the parts being
joined is predominantly equal from tens of a millimeter
up to 1--3 mm (less often 4--8 mm) [1]. One of the
important points in selection of a particular aluminium
alloy for fabrication of elements of the above structures is the maximum possible reduction of the total
product mass at preservation of their mechanical characteristics. This approach necessitates application of
alloys with different alloying systems. In critical modern structures a transition is in progress from alloys
of Al--Mg--Mn (AMg6 alloy) and Al--Cu--Mg (D16
alloy) alloying systems to alloys, for instance, of Al-Mg--Li system (1420 alloy), having high mechanical
characteristics at low density and improved modulus
of elasticity [2].
In fabrication of structures with the above range
of wall thicknesses of individual elements, laser welding (LW) can be used in addition to arc and plasma
(microplasma) welding processes [3]. This process was
not widely accepted in practice, primarily, because of
the high cost of process lasers. However, application
of laser-arc welding allows lowering the cost of one
running meter of weld by approximately 50 % due to
partial replacement of laser power by arc power and
increasing process efficiency by 50 % [4]. Such a process should allow retaining most of LW advantages
and making it more attractive for the user.
Experimental studies were preceded by analysis of
publications devoted to laser-arc hybrid welding of
aluminium alloys for a more accurate determination
of welding mode parameters. Study [5] deals with the
technological features of welding aluminium and its
alloys by radiation of CO2 laser of power P = 0.6 kW
in combination with non-consumable tungsten electrode arc. It was proposed to weld 5052 alloy of thickness δ = 3.2 mm at speed vw = 30.5 m/h and current
Iw = 70 A in a shielding atmosphere of helium. Ratio
of laser to arc power was equal to approximately 1:3.
In view of the low power of laser radiation, the nature
of weld formation was typical for arc welding. At the
ratio of laser to arc power of approximately 1:1, weld
formation had the form of a keyhole, which was close
to that characteristic for LW [6, 7]. At increase of
laser radiation power from 0.1 to 1.5 kW (10 mm arc
length) to achieve reliable penetration, speed rose
© V.D. SHELYAGIN, V.Yu. KHASKIN, V.S. MASHIN, M.P. PASHULYA, A.V. BERNATSKY and A.V. SIORA, 2009
12/2009
21
Figure 1. Schematic of conducting experiments on laser-arc hybrid
welding: 1 ---- laser radiation of power P; 2 ---- focusing lens with
focal distance F; 3 ---- shielding nozzle; 4 ---- welding wire; 5 ---copper current-conducting nozzle; 6 ---- sample; ∆F ---- immersion
of radiation caustic neck relative to sample surface; L ---- distance
between the consumable electrode tip and laser radiation axis
from 0.5 to 2.0 m/min. Ratio of penetration depth
to weld width varied from 0.5 up to 2.0, while the
heat input changed from 3.2 to 0.5 kJ/cm.
It is noted in [8] that unlike LW, in which the
gap between the abutted elements should not be more
than 10 % of metal thickness, in hybrid welding this
parameter can be equal to 25--30 %. Work [9] deals
with hybrid welding of aluminium alloys by radiation
of CO2 and Nd:YAG lasers in the power range from
0.4 up to 6.0 kW. The criterion of cracking susceptibility lowering was used to select the mode of hybrid
welding of 6000 series aluminium alloy (δ = 2 mm),
which exceeded LW by 40 % in terms of speed. The
review work by German scientists [10] separately considers the technological capabilities of the combined
laser-arc welding (in which the arc and laser beam
act on the product at a certain distance from each
other), and hybrid welding (both heat sources acting
on one item within a common weld pool). The authors
give special attention to welding aluminium alloys by
a hybrid of laser radiation and consumable-electrode
arc and even consider a twin-arc hybrid process. In
review work [11] the recommended range of variation
of the distance between focused radiation of Nd:YAG
laser and consumable electrode arc was equal to 0-10 mm (better 4--10 mm) for welding aluminium alloys (5052 and 6008). The arc current was varied in
the range of Iw = 60--240 A, with continuous laser
radiation power P = 1.5--3.5 kW.
Analysis of the published data can lead to the conclusion that for hybrid welding of aluminium alloys
of thickness δ = 4--6 mm, it is rational to use laser
Table 1. Mechanical properties of welded aluminium alloys
Alloy
σt, MPa
σ0.2, MPa
σ0.01, MPa
δ5, %
D16
458--462
460
318--348
330
235--265
257
14.6--16.2
15.4
1420
465--477
470
236--252
244
--
9.1--10.1
9.5
22
radiation with wave length 1.06 µm in the power range
P = 2--5 kW and consumable-electrode arc. The power
ratio of laser radiation and arc should be within 1:1
up to 1:1.5.
This study was aimed at optimizing the technique
and technological parameters of the modes of welding
aluminium alloys AMg6, 1420 and D16 by the hybrid
process using radiation of Nd:YAG laser and consumable electrode pulsed arc (CEPA), as well as studying
the technological features of such hybrid laser-arc
welding.
To achieve the defined aim, we have conducted a
number of experiments according to the schematic
given in [12] (Figure 1). As shown in [13], this schematic is fully suitable for aluminium alloy welding.
Used as the laser radiation source was Nd:YAG laser
of DY 044 model (Rofin Synar, Germany) with radiation power of up to P = 4.4 kW. Consumable electrode pulsed arc was powered by Fronius TPS-2700
system (Austria), providing welding current of up
Iw = 270 A.
The hybrid head was placed on a manipulator,
moving it relative to a stationary sample, clamped in
the welding jig. Samples of 300 × 100 × δ mm size
were butt-welded. Alloys AMg6 (δ = 6 mm), D16
(δ = 5 mm) and 1420 (δ = 4 mm) (GOST 4784--74),
and 1.2 mm wires SvAMg6 and SvAK5 (GOST 7871-75) were used. Mechanical properties of the metals
being welded were determined before conducting the
experiments (Table 1). Tensile testing of the samples
was performed in UME-10TM machine. Welding was
conducted on a removable stainless steel backing with
2 mm groove in argon (GOST 10157--79) or helium
of grade B (TU 51-940--80) fed with the flow rate of
20 and 30 l/min, respectively. Welding was performed by «backward inclined» electrode. The angle
of the axis of laser radiation inclination relative to
the normal to the sample was equal to 9°, and the
angle of the arc torch inclination was 55°. Welding
speed was varied in the range of vw = 30--60 m/h. At
the moment of completion of each experiment on hybrid welding, when the welding head stopped, first
CEPA was switched off, and in 1--2 s the laser radiation was off, thus allowing accurate determination of
the position of the focused laser radiation relative to
the zone of CEPA action. The greatest penetration
depth corresponded to 2--4 mm distance. In addition,
the relative influence of laser radiation power and
electrode wire feed rate (welding current) on electric
parameters of CEPA process was studied.
The following procedure was accepted for investigations performed to select the modes of hybrid welding of AMg6, D16 and 1420 alloys. A stable formation
of the weld root at minimum power of both the heat
sources and maximum welding speed vw was a criterion
for mode optimization. A combination of the laser and
arc source powers was selected close to the ratio of
1:1 recommended in publications. Mode selection was
performed by making sample beads and their welding.
Geometrical parameters of the welds were determined
12/2009
Table 2. Influence of modes of CEPA and CEPA-laser hybrid welding of AMg6 aluminium alloy in argon on weld geometrical parameters
Sample #
vw, m/h
Iw, À
Ua, V
vf, m/h
Ð*, kW
Â, mm
Í, mm
b, mm
h, mm
1
30
126
20.0
8.3
--
9.0
3.0
--
--
2-1
30
113
21.9
8.3
2
9.5
2.7
--
--
2-2
30
119
20.6
8.3
2
10.0
3.0
--
--
3
30
121
20.1
8.3
3
--
--
--
--
4
30
120
20.0
8.3
4
9.0
2.5
5.0
2.0
15
30
119
19.0
7.5
--
8.0
2.8
--
--
14
30
111
20.5
7.5
4
14.0
2.5
2.5
1.0
16
30
130
20.5
8.3
--
8.8
2.7
--
--
18
30
122
21.0
8.3
4
14.2
1.5
5.5
1.4
17
30
145
21.5
9.3
--
9.0
3.3
--
--
19
30
138
21.5
9.3
4
16.0
2.0
4.0
1.3
20
45
131
19.6
8.3
--
6.2
2.7
--
--
12
45
123
21.1
8.3
4
11.0
2.3
--
--
22
45
150
21.3
9.3
--
8.5
2.2
--
--
11
45
142
21.1
9.3
4
12.0
2.0
3.0
1.2
23
45
164
21.9
10.1
--
9.0
2.3
--
--
21
45
156
22.6
10.1
4
13.0
2.0
--
--
25
60
150
21.0
9.3
--
7.0
2.2
--
--
6
60
140
21.7
9.3
4
10.0
2.2
--
--
27
60
177
22.0
10.9
--
8.0
2.5
--
--
9
60
162
22.4
10.9
4
11.0
1.5
--
--
26
60
198
22.3
12.2
--
8.5
2.2
--
--
24
60
194
23.0
12.2
4
12.0
2.0
--
--
7
60
126
20.5
8.3
4
9.0
2.0
--
--
8
60
157
22.0
10.1
4
10.0
2.0
--
--
10
60
182
23.7
11.6
4
12.0
1.7
--
--
*
Continuous radiation with 1.06 µm wave length.
from transverse macrosections with the accuracy of
±0.1 mm. Weld width B, their reinforcement height
H, width b and height h of the weld root at complete
penetration of the metal (Table 2), weld depth (in
case of metal incomplete penetration) and weld crosssectional area S in different weld zones were measured.
Quantity and diameter of pores and voids in the welds
were also evaluated. Weld macrostructure was revealed by chemical etching of the sections in a solution, consisting of three acids ---- 72 cm3 HCl + 24 cm3
HNO3 + 4 cm3 HF. Strength characteristics of welded
joints were determined using samples with weld reinforcement and removed root.
During experiments it was established that 5--10 s
after the start of hybrid welding an intensive absorption of laser radiation by plasma plume forming above
the weld pool began, leading to reduction of penetration depth. In our opinion, this is related to intensive
evolution of welding aerosols forming above the melt
pool under the action of the melting electrode [14].
12/2009
Investigations conducted at PWI showed [15] that
with current increase in inert-gas consumable-electrode welding the average temperature of electrode
metal drops rises, reaching that of boiling of aluminium alloy, from which electrode wire is made. At
unchanged welding current, increase of wire diameter
leads to lowering of average temperature of electrode
metal drops. With increase of helium content in helium-argon mixtures, drop temperature also decreases,
reaching the lowest values in welding in pure helium
[15]. This, in its turn, leads to lowering of magnesium
evaporation in the drops, increase of its content in the
weld, and improvement of mechanical properties of
the joints. In CEPA + laser hybrid welding, glowing
of laser radiation above the weld pool near CEPA
action zone was observed, which is indicative of a
greater absorption of radiation. The number of electrode metal drops and volume of products of evaporation from them and base metal increase with increase
of wire melting rate (welding current) [14]. This in-
23
Table 3. Weld shape depending on welding speed and feed rate of SvAMg6 electrode wire in CEPA welding and CEPA-laser hybrid
welding of AMg6 alloy
Welding mode
CEPA*
vw, m/h
vf, m/min
30
7.5
CEPA + LW* (P = 4 kW)
8.3
45
8.3
9.3
60
10.9
12.2
*
Section numbers correspond to sample numbers from Table 2.
24
12/2009
creases the gas atmosphere density, promotes absorption of laser radiation and reduction of penetration
depth, respectively.
As shown in [16], at LW in helium and in argon,
the process of weld pool metal evaporation will be
different. At evaporation in helium a more intensive
lateral unloading of the vapour plume results in an
essentially lower density of metal vapours in the path
of laser radiation, than that found in evaporation in
argon. This accounts for the observed effect of achievement of a stable deep penetration, when helium or
helium-containing mixtures are used.
In connection with the assumption of a change of
spreading of metal vapours formed above the weld
pool in a particular shielding gas, it was proposed to
use pulsed radiation instead of continuous radiation.
It was anticipated that in the case of argon shielding,
metal vapour spreading necessary for elimination of
laser radiation shielding will take place during the
pause. The ratio of the time of radiation pulse and
pause was selected by the criterion of absence of the
characteristic reduction of penetration depth in the
hybrid process. The selected ratio was equal to 3:1,
i.e. pulse ratio Qp = 3 at pulse repetition rate f =
= 250 Hz. Such a pulsed radiation mode allowed conducting hybrid welding in argon shielding gas. It is
possible that the selected ratio is not optimum, and
pulse repetition rate of laser radiation should in a
certain way correspond to the consumable electrode
arc pulse frequency. This aspect, obviously, requires
further investigation.
Table 3 gives an example of the influence of modes
of AMg6 alloy welding on weld shape. It is seen from
the Table that in the range of welding speeds vw =
= 30--45 m/h and electrode wire feed rates vf = 7.5-9.3 m/min CEPA cannot completely penetrate a sample of AMg6 alloy, unlike CEPA + laser. Optimum
modes of argon-shielded CEPA + laser hybrid process
are observed at vw = 30 m/h, P = 4 kW, Iw ≈ 120 A
and vw = 45 m/h, P = 4 kW, Iw ≈ 140 A. Helium
application enables increasing the welding speed up
to 60 m/h at simultaneous lowering of radiation
power and CEPA current (Figure 2). Results of argon-shielded hybrid welding of D16 alloy using pulsed
laser radiation with the peak power Ppeak = 4 kW and
average power Pav = 3 kW are shown in Figure 3. The
optimum mode for such a welding process is Iw =
= 200 A, Ua = 21.5 V, vf = 12.4 m/min. Application
of pulsed radiation necessitated an increase of CEPA
power, however, the penetration shape, HAZ and
grain size remained on the level characteristic for con-
Figure 2. Macrosection of a joint of AMg6 alloy made by heliumshielded hybrid process: vw = 60 m/h; P = 3 kW; Iw ≈ 74 A; Ua =
= 17 V
tinuous radiation hybrid welding (Table 3). At the
same wire feed rate (vw = 30 m/h), the CEPA + LW
hybrid process allows increasing weld width 1.6--1.9
times and lowering their reinforcement height H 1.1-1.6 times, compared to CEPA welding. Such dependencies are also observed at higher welding speeds, but
at lower absolute values of geometrical parameters of
welds. A characteristic drawback of hybrid welding
is pore formation in the welds. In welding of the
considered alloys, this phenomenon is the most pronounced in alloy 1420 (Figure 4). This, in all prob-
Table 4. Modes of hybrid welding of aluminium alloy butt joints
(vw = 60 m/h)
Alloy (wire)
Iw, À
Ua, V
vf, m/min
Ð, kW
D16 (SvAMg6)
185--190
21.5--21.6
11.6
4.0
D16 (SvAK5)
190--200
22.5--23.0
10.3
4.0
48--50
13.8
3.1
2.0
1420 (SvAMg6)
12/2009
Figure 3. Macrosections of butt joints of D16 alloy made by hybrid
welding with pulsed laser radiation in argon with SvAMg6 wire
(Pav = 3 kW, Ppeak = 4 kW, Qp = 3, f = 250 Hz, vw = 60 m/h):
a ---- Iw ≈ 185 A, Ua ≈ 21.5 V, vf = 11.6 m/min; b ---- Iw ≈ 200 A,
Ua ≈ 21.5 V, vf = 12.4 m/min; c ---- Iw ≈ 210 A, Ua ≈ 21.5 V, vf =
= 13.0 m/min
25
Figure 4. Influence of CEPA welding mode parameters (vw =
= 60 m/h) in hybrid welding (continuous radiation, P = 2 kW)
in argon on geometrical parameters of 1420 alloy weld: a ---- Iw =
= 40 A, Ua = 12.3 V, vf = 2.3 m/min; b ---- Iw = 42 A, Ua = 12.5 V,
vf = 2.7 m/min; c ---- Iw = 51 A, Ua = 14.3 V, vf = 3.1 m/min
ability, is related to intensive evaporation of lithium
and magnesium from the base metal under the impact
of laser radiation.
It is established that irrespective of wire feed rate
(from 7.5 up to 13.2 m/min) laser radiation of 4 kW
power increases arc voltage (observed arc length) by
1--2 V and decreases welding current by 10--15 A.
With increase of laser radiation power from 1 up to
Figure 5. Influence of heat input q of CEPA (1) and CEPA + laser
(2) welding of AMg6 alloy using continuous radiation of power
P = 4 kW on weld width B (a), penetration depth δb.m + h (b) and
weld cross-sectional area ΣS (c)
Table 5. Mechanical properties of aluminium alloy joints made by hybrid welding
σt, MPa
σ0.2, MPa
σ0.01, MPa
b.m
σw.j
t /σt
b.m
σw.j
0.2 /σ0.2
D16* (SvAMg6)
290--324
304
229--238
234
101--161
139
0.66
0.71
D16** (SvAMg6)
291--300
294
211--218
216
96--122
111
0.64
0.65
D16* (ÑâÀÊ5)
311--326
319
236--245
240
126--155
139
0.69
0.77
D16** (SvAK5)
286--306
293
200--228
217
93--134
117
0.64
0.66
1420* (SvAMg6)
293--318
302
179--184
181
86--96
92
0.64
0.74
1420** (SvAMg6)
275--308
294
167--180
173
91--120
106
0.63
0.71
Alloy (wire)
*
Weld root reinforcement was removed in the samples.
26
**
Upper reinforcement and weld root reinforcement were removed in the samples.
12/2009
4 kW at constant electrode wire feed rate, a reverse
dependence is observed ---- welding current rises and
arc voltage decreases (Tables 2 and 4). This is related,
primarily, to increase of arc region ionization by laser
radiation and change of the arc volt-ampere characteristics, respectively.
Another important parameter, characterizing the
welding process, is the heat input, which was determined for arc and hybrid welding of AMg6 alloy.
Here, the argon-arc welding efficiency was taken to
be 0.72, and that of helium-arc welding was 0.88 [17].
The efficiency of the hybrid process laser component
was taken to be a unity, as deep penetration welding
was performed. The calculations allowed plotting a
dependence of heat input influence on weld width,
their total height (penetration depth δ and weld root
height h), as well as cross-sectional area of the remelted metal (Figure 5). It is established that at the
same heat input, the hybrid welding compared to
CEPA welding allows increasing the depth of metal
penetration, as well as reducing weld width and crosssectional area.
Analysis of the results of mechanical testing of
high-strength aluminium alloys showed (Table 5) that
D16 alloy joints made with SvAK5 wire have higher
strength characteristics than joints welded with
SvAMg6 wire. In all the cases, fractures in D16 alloy
joints start from the zone of fusion of the weld root
with the base metal and propagate into the weld. 1420
alloy joints, both with and without upper reinforcement, fail in the weld center. Coefficients of strength
of D16 and 1420 alloy joints made by laser-MIG hyb.m
brid welding are equal to σw.j
= 0.63--0.69, and
t /σt
b.m
of yield point of the joints σw.j
/σ
0.2
0.2 = 0.65--0.77.
Removal of upper and weld root reinforcement leads
to a certain lowering of the strength properties of the
joints.
CONCLUSIONS
1. In laser-MIG hybrid welding (CEPA + LW) of
aluminium alloys the intensity of evaporation of individual elements from the base metal and electrode
wire, as well as the composition of the shielding gas
atmosphere, have an essential influence on laser radiation propagation to the metal being welded. Use
of argon and high welding currents leads to radiation
shielding, and, hence, considerable reduction of penetration depth. To eliminate this effect, it is rational
to apply mixtures of argon with helium or pure helium
for weld pool shielding, and also use pulse modulation
of laser radiation.
2. In the speed range of 30--60 m/h, hybrid welding, compared to CEPA welding, allows increasing
1.8 to 2.6 times the speed of welding metal 6 mm
12/2009
thick, lower 1.3--1.6 times the heat input into the
metal being welded and considerably lower deformations of joints 4 mm thick. Investigation of the nature
of weld formation leads to the conclusion that in hybrid welding of metal of 6 mm and greater thickness
with application of laser radiation of 1--4 kW power,
the CEPA process has the leading role.
3. Such characteristic defects as porosity and blowholes in hybrid welding of aluminium alloys of Al-Mg--Mn, Al--Cu--Mg and Al--Mg--Li alloying systems
can be eliminated by improving the weld pool shielding, as well as thorough selection and optimization of
welding modes.
4. Such mechanical characteristics of welded joints
as strength and yield, are somewhat higher for the
hybrid process than the level of similar values obtained, when CEPA is used. Taking into account an
increase of efficiency, this demonstrates the rationality
of CEPA process replacement by CEPA + LW process.
1. Rabkin, D.M. (1986) Metallurgy of fusion welding of aluminium and its alloys. Kiev: Naukova Dumka.
2. Shakhov, S.V. (2007) Technological and metallurgical specifics of laser welding of current aircraft aluminium alloys:
Syn. of Thesis for Cand. of Techn. Sci. Degree. Moscow.
3. (1974) Technology of fusion electric welding of metals and
alloys. Ed. by B.E. Paton. Moscow: Mashinostroenie.
4. Irving, B. (1994) Automative engineers plunge into tomorrow’s joining problems. Welding J., 73(11), 47--50.
5. Diebold, T.P., Albright, C.E. (1984) Laser-GTA welding of
aluminum alloy 5052. Ibid., 63(6), 18--24.
6. Wendelstorf, J., Decker, I., Wohlfahrt, H. (1994) Laser-enhanced gas tungsten arc welding (laser-TIG). Welding in
the World, 34, 395--396.
7. Moeniralam, Z., Luijendijk, T. (1996) Wisselwerking tussen
laserlassen en booglassen. Lastechniek, 62(7/8), 3--6.
8. Walduck, R.P., Biffin, J. (1994) Plasma arc augmented laser welding. Welding and Metal Fabric., 62(4), 172--176.
9. Blundell, N.J. (1998) Arc takes laser welding into new territory. Materials World, 9, 537--538.
10. Dilthey, U., Wieschemann, A. (2000) Prospects by combining and coupling laser beam and arc welding process.
Rivista Italiana della Saldatura, 52(6), 749--759.
11. Katayama, S. (2008) Development of hybrid laser-arc welding. Welding Technology, 56(2), 51--58.
12. Shelyagin, V.D., Khaskin, V.Yu., Garashchuk, V.P. et al.
(2002) Hydrid-CO2-laser and CO2 consumable-arc welding.
The Paton Welding J., 10, 35--37.
13. Shelyagin, V.D., Khaskin, V.Yu., Naboka, T.N. et al.
(2005) Hybrid laser-arc welding of carbon steels and aluminium alloys. Dopovidi NAN Ukrainy, 7, 97--102.
14. Levchenko, O.G., Mashin, V.S. (2003) Sanitary-hygienic
characteristics of the process of consumable-electrode inertgas welding of AMg6 aluminium alloy. The Paton Welding
J., 1, 46--48.
15. Ishchenko, A.Ya., Mashin, V.S., Dovbishchenko, I.V. et al.
(1994) Mean temperature of electrode metal drops in inertgas shielded welding of aluminium alloys. Avtomatich.
Svarka, 1, 48--49.
16. Sukhorukov, S.B., Krivtsun, I.V., Sidorets, V.N. (2009)
Mathematical modeling of gas dynamics, heat- and mass exchange in metal vapor flow during deep penetration laser
welding. In: Proc. of 4th Int. Conf. on Mathematical Modeling and Information Technologies in Welding and Related Processes (27--30 May, 2008, Katsiveli, Crimea).
Kiev: PWI, 155--164.
17. Ishchenko, A.Ya., Mashin, V.S., Budnik, V.P. (1995) About
porosity of welds in consumable-electrode inert-arc welding of
aluminium alloys. Avtomatich. Svarka, 1, 16--18, 22.
27
APPLICATION OF PLASMA-ARC METALLISATION
FOR RESTORATION OF WHEEL PAIRS
1
1
1
1
1
V.I. ZELENIN , P.M. KAVUNENKO , V.V. TISENKOV , V.M. TEPLYUK , M.A. POLESHCHUK ,
2
2
3
3
3
3
V.D. LEBED , V.I. LIPISY , S.V. BONDAREV , S.A. GAVRILOV , N.T. OLGARD and S.A. CHEBUROV
1
E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
2
SE PKTB TsV UZ, Kiev, Ukraine
3
SE UkrNIIV, Kremenchug, Ukraine
Method for repair of journals and under-hub parts of axles of freight carriage wheels by plasma-arc metallisation is
considered, results of fatigue rig tests with the recommended service life of the repaired axles are presented.
K e y w o r d s : plasma-arc metallisation, axial flow, intermediate anode, wheel pairs, journals, under-hub parts, coating
structure, resistive-strain sensor
Railway transportation has several tens of thousands
of wheel pairs, the axles of which have been rejected
because of defects of journals and under-hub parts of
axles, namely wear, scoring, scratches, work-hardening of the journal. Reconditioning of these parts allows
them to be reused, thus yielding a considerable cost
saving.
The material for carriage axles is carbon steel of
OSV grade (GOST 4728--96) with carbon content of
0.38--0.47 %, which is characterized by a high wear
resistance and contact fatigue strength.
Successful reconditioning of wheel pair axles is
performed in Germany, Sweden, Rumania, Russia, as
well as in other countries [1--3].
PWI and PKTB TsV UZ developed a new technology of plasma-arc metallisation in an inert atmosphere.
Technique of such coating spraying differs by that
atomisation is performed by the plasma arc in argon
by a current-conducting wire-anode, which is the initial material for coating formation, with simultaneous
mechanical treatment of the latter by a special brush
device, cleaning the coating from oxides and particles
hitting it at a high angle.
In this work an argon-arc plasmatron with a tungsten cathode and air cooling was used for coating
spraying. Ignition was performed to an intermediate
air-cooled anode, forming the plasma jet. After ignition the electric potential shifts to the atomized wire.
Wire application as the atomized anode improves process efficiency, and plasma energy is consumed in wire
atomization and producing coatings, and not plasmatron heating. The cathode is in argon atmosphere, thus
increasing its resistance.
Argon plasma flow is axially blown over by an air
flow around the circumference, which simultaneously
cools the plasmatron, having a qualitative effect on
the plasma shape and composition.
The mode of the blowing flow was selected so that
the pressure in it was equal to that of the plasma jet.
Conditions were created, when the contours of the
visible cone of outflowing plasma were almost parallel, which was indicative of a slight mixing of plasma
with the cooling air.
In view of the considerable difference of temperature of the plasma flow and the axially outflowing
air flow, no flow mixing is observed. Presumably,
because of the high velocity of the outflow, the zone
with maximum argon content is of a considerable (up
to 150--200 mm) length, thus allowing spraying to be
performed in it without any significant oxidation.
The above-said is in good agreement with the data
obtained from the calculation models (Figure 1, a,
b) [4].
Used as coating material was wire from steels 65G,
70, 20Kh, 30KhDS, as well as flux-cored wires [5].
The proposed technology allows lowering coating
porosity to 2--5 %, eliminating oxide formation and
increasing the adhesion of the obtained coating to the
substrate up to 40--60 MPa. Figure 2 gives the microstructure of a coating, produced by plasma-arc metallisation with wire from steel 65G. No porosity, oxides or other defects were found in it. Coating hardness
was HRC 30--35, which corresponds to the code documentation. Indices of the coating mechanical properties and composition are close to those of steel of OSV
grade.
Figure 3 shows the general view of KT-088 system
for reconditioning the journals and under-hub part of
wheel pair axles, developed and manufactured at PWI
and PKTB TsV UZ. The system is a plasmatron with
the current source and sound-absorbing chamber with
the axle fixed in it.
Spraying is performed by air-cooled plasmatron
(14--16 kW power) in argon, thus greatly increasing
the service life of the plasmatron nozzle (more than
100 h) (Figure 4). Before metallisation, the axle surfaces to be reconditioned are turned to the required
size, hardened by rolling, degreased and activated by
metal shot DChK-1-3. Deposition of not more than
© V.I. ZELENIN, P.M. KAVUNENKO, V.V. TISENKOV, V.M. TEPLYUK, M.A. POLESHCHUK, V.D. LEBED, V.I. LIPISY, S.V. BONDAREV, S.A. GAVRILOV,
N.T. OLGARD and S.A. CHEBUROV, 2009
28
12/2009
Figure 1. Calculated distribution of relative concentration of argon CAr in the plasma jet outflowing into the air space without blowing
(a), with blowing (b), and appearance of plasma flow (c)
2 mm coatings on wheel pair axle is followed by its
machining.
Table 1 gives the data on measurement of hardness
after spraying of a pair of journals of axles of RU1
and RU1Sh types by wire from steel of grade 65G.
External examination and metallographic studies
of reference samples confirmed the satisfactory condition of the coatings sprayed on the axle journals.
Press-fitting and pressing-out of wheels on the axle
under-hub part were performed in Darnitsa railway
car repair works by a standard technology. Press-fitting force was equal from 630 up to 800 kN, depending
on tightness. Pressing-out was performed one week
after press-fitting. External inspection of the axle under-hub part showed the satisfactory condition of their
surface ---- no scratches, spallation or cracks.
Figure 2. Microstructure of a coating from steel 65G produced by
plasma-arc metallisation
12/2009
The developed technology of reconditioning the
journals and under-hub part of the axles has the following advantages:
• process of plasma-arc metallisation does not
lower the strength properties of the reconditioned part
(item heating to not more than 200 °C) and does not
affect its mechanical properties;
• does not cause distortion of the reconditioned
part;
• allows spraying a coating of thickness from 0.1
up to 20 mm;
• porosity is not more than 2--4 %;
• a high stability of the spraying process is found
(service life of the nozzle forming the plasma arc and
Figure 3. General view of KT-088 unit for reconditioning the journal and under-hub part of wheel pair axle by plasma-arc metallisation
29
Table 1. Hardness values of axle journal after spraying
Axle type
RU1Sh
RU1
Axle number
Average HB hardness value of
journal surface
Right
Left
42097
343
358
52073
319
305
42827
312
344
49764
387
376
Note. After spraying axle journal is ground to album size. 2.
Hardness measurements of each journal surface were taken in five
points by TDM-1 hardness meter.
Figure 4. Process of plasma-arc metallisation of axle journal
of plasmatron cathode is not less than 100 h of machine
time).
Conducted research work demonstrated the rationality of application of plasma-arc metallisation in
enterprises of carriage facilities of Ukrzaliznitsa. Further testing of axles in SE UkrNIIV confirmed the
obtained results.
Fatigue testing of axles was conducted in hydropulsator rig TsDM-200Pu by the coordinated and
approved PM 07.00307--2007 «Axles with reconditioned journals and under-hub parts (types RU1 and
RU1Sh). Program and procedure of fatigue testing».
Before testing the cut up axle samples were fitted
with resistive strain-sensors for adjustment and monitoring of testing mode. Figure 5 shows the schematic
of axle sample loading with the indicated location of
resistive strain-sensors. A sample was mounted in the
rig on two supports. Load was applied to under-hub
part of axle sample through a special pusher. Support
spacing and point of application of load P were selected proceeding from the capabilities of the testing
equipment and need to guarantee fatigue fracture of
the axle journal in the fillet zone.
Based on calculation results, support spacing is
taken to be 1000 mm, arm of vertical load application
was 730 mm (see Figure 5) from the right support,
vertical load being not more than P = 883 kN.
Testing of fatigue samples was conducted by the
method of multiple cyclic loading at asymmetrical
cycle with asymmetry of 0.1 at different load levels.
Fatigue cracks were determined by organoleptic
method (visually) using kerosene test.
All samples were tested at five loading levels: five
samples of axles of type RU1 ---- on four levels, and
four samples of axles of type RU1Sh ---- on three
levels.
Eight samples failed in fillet transition from axle
journal to its under-hub part. One sample withstood
the base number of 5⋅106 cycles of loading without
fatigue damage or failures. Figure 6 shows the appearance of fracture of the failing sample of axle journal.
After testing maximum stresses σmax in the fracture
zone were found from the following formula:
σmax = 0.73
aP
[MPa],
W
where W is the moment of axle journal resistance in
the fracture site, mm3.
Moment of axle journal resistance W was determined by the following formula:
W=
πD3
,
32
where D is the axle journal diameter in the fracture
site, mm.
Figure 5. Schematic of axle sample loading: a ---- distance from
support to fracture site
30
Figure 6. Appearance of fracture of failed sample of axle journal
12/2009
Endurance limit in the journal fillet zone at symmetrical loading cycle was equal to 167 MPa for axles
of type RU1, and 189.5 MPa for type RU1Sh.
As during testing the number of samples of each
axle type was small, and years of their manufacturing
were different, the probabilistic-statistical treatment
was conducted by the results of testing all the samples.
Endurance limit was equal to 149.5 MPa.
For new parts endurance limit in the zone of journal fillet at symmetrical loading cycle on the base of
5⋅106 cycles should be not lower than 195 MPa, thus
ensuring the average service life of carriage axles of
15 years, in keeping with the requirements of GOST
30237--96 [6].
All the axles to be reconditioned should be subjected to ultrasonic testing.
Determination of the increase of surface hardness
and depth of the hardened layer after rolling was
performed on samples made from the journal and under-hub part of the axle, which was not tested for
fatigue, in keeping with the requirements of the standards [7, 8].
Increase of surface hardness ∆ after axle rolling
was determined by the following formula:
∆=
Hsurf -- Hb
⋅100 [%],
Hb
where Hsurf is the highest value of surface hardness;
Hb is the initial hardness of unhardened metal, which
was determined on one of the sides normal to axle
surface at the depth of 15--20 mm.
Results of calculation of increase of surface hardness and depth of hardened layer after rolling are
given in Table 2.
At present the batch of reconditioned axles is going
through operational testing according to testing program in the closed testing route Rokovataya--Uzhgorod--Koc′ice.
Thus, by the results of fatigue testing on the base
of 5⋅106 loading cycles of axles of type RU1 and
RU1Sh of freight carriage wheel pairs with journals
and under-hub parts reconditioned by the technology
of plasma-arc metallisation, the endurance limit in the
journal fillet zone is equal to 149.5 MPa, which is
0.76 of the standard value (195 MPa), and corresponds
12/2009
Table 2. Results of calculation of increase of surface hardness
and hardened layer depth after rolling acc. to [6, 7]
Controlled characteristic
Parameter value
Standard
Actual
journal
22
24.9
under-hub part
22
29.6
journal
2.6--5.2
3.2
under-hub part
3.9--7.8
4.0
Hardness increase after rolling compared to initial value, not less than, %:
Hardened layer depth, mm:
to average service life of 11.4 years. Considering that
axles of different services lives and types, as well as
different years of manufacturing, will be reconditioned, it is recommended to specify 10 years service
life for the reconditioned axles.
Technology of plasma-arc metallisation of journals
and under-hub parts of wheel pair axles allows increasing the surface hardness and depth of the hardened layer after rolling, in keeping with the standard
requirements.
1. Kuzmin, V.P., Berdin, M.M., Kuleshov, E.S. et al. (2002)
Reconditioning of axle journals of wheel pairs by spraying.
Zheleznodorozhn. Transport, 1, 46--49.
2. TI 32-VNIIZhT0501/6--95: Technological instruction. Introd. 05.06.95.
3. Kuzmin, V.P., Purekhov, A.N. (2002) Reconditioning of
axle journals of car wheel pairs by arc metallisation.
Zheleznodorozhn. Vestnik VNIIZhT, 1, 46.
4. Kharlamov, M.Yu., Krivtsun, I.V., Korzhik, V.N. et al.
(2008) Effect of the kind of concurrent gas flow on characteristics of the arc plasma generated by plasmatron with anode wire. The Paton Welding J., 6, 14--18.
5. Zhadkevich, M.L., Zelenin, V.I., Teplyuk, V.M. et al.
(2007) Reconditioning of axle journals of railway transport
by plasma-arc metallisation. In: Proc. of 7th Annual Int. Industr. Conf. on Effectiveness of Realisation of Scientific
Resource and Industry Potential under Current Conditions
(9--13 Febr. 2007, Slavsk). Kiev, 417--418.
6. GOST 30237--96: Finishing axles for rolling-stock of 1520-mm
track. Specifications. Introd. 01.01.96.
7. TI 32 TsV VNIIZhT--86: Technological instruction of roll
hardening of car wheel pair axles. Introd. 01.07.87.
8. (1996) Codes of design of railway cars (non-self-propelled)
of Ministry of Railways of 1520 mm track. Moscow: GosNIIV-VNIIZhT.
31
REPAIR WELDING OF TURBINE CASE PARTS
FROM HEAT-RESISTANT STEELS
WITHOUT SUBSEQUENT HEAT TREATMENT*
1
1
1
2
2
3
A.K. TSARYUK , V.D. IVANENKO , V.V. VOLKOV , S.I. MAZUR , A.A. TROJNYAK , A.V. VAVILOV ,
3
3
A.G. KANTOR and N.P. VOLICHENKO
1
E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
2
Tripolskaya TPP, Ukrainka, Ukraine
3
OJSC «Turboatom», Kharkov, Ukraine
The paper deals with the issues of repair welding of damaged case parts of turbines after long-term operation at steam
working parameters. A technology of welding with pearlitic electrodes without subsequent heat treatment (high tempering)
is proposed. For repair of damaged components of case equipment of turbo units from cast heat-resistant steels a technology
of manual arc welding with pearlitic electrodes of E-09Kh1M type is recommended. This technology involves application
of preheating and concurrent heating with subsequent thermal recovery. Welded joints made by the developed technology
have high crack resistance and required mechanical properties. The proposed technology has been successfully tested in
repair welding of HPC of K-300-240 turbine.
K e y w o r d s : repair welding, damage, heat-resistant cast
steels, turbine case parts, electrodes, preheating, thermal recovery, residual life
Extension of service life of power equipment of thermal power plants (TPP) is possible after examination
of the condition of its individual components and technical diagnostics to reveal damage, detection of which
requires conducting repair work to ensure further operation of the units. Damage of elements of equipment,
which has been in operation in TPP for a long time,
is due to technological, design and service factors.
One of the most damaged elements of turbo units are
turbine case parts, namely high (HPC) and mediumpressure cylinders, cases of steam distribution regulating valves, high-pressure steam-water fittings, etc.
[1]. A number of such parts are of a complex configuration and are made of cast heat-resistant complex-alloyed steels (15Kh1M1FL, 20KhMFL and 20KhML).
Turbine case parts exposed to high pressure and temperatures have damage in the form of cracks caused
by metal creep, thermal fatigue and brittle fracture.
In most of the cases this damage is located in part
sections with an abrupt change in thickness or in casting defect zones. Increased damageability also develops in regions of welding, made with technology violations [2]. Repair of damaged parts runs into certain
difficulties related to supporting work performance
under production conditions. Therefore, development
of advanced technologies of welding as the main process of power equipment repair is an important and
urgent task to extend the life and guarantee safe operation of TPP power units [3].
Welding of cast chromium-molybdenum steels presents certain difficulties and is usually performed with
application of preheating and concurrent heating of
welding regions, as well as their subsequent heat treatment. Considering that under the conditions of operating TPP conducting heat treatment of repaired
welded joints is problematic, application of welding
processes without post-weld heat treatment is highly
attractive. Work in this area is performed in specialized RF organizations (OJSC «VTI», SPA «TsKTI»,
SPA «TsNIITMash», etc.), which was reflected in
standard RD 108.021.112--88 [4] and other sources
[1--3, 5]. It is recommended to perform repair welding
without heat treatment by austenitic electrodes without preheating or pearlitic electrode with preheating
and concurrent heating and false heating of certain
zones of the repaired section [1, 4].
Experience of application of electrodes of austenitic class is indicative of a considerable inhomogeneity
of the deposited metal composition and mechanical
properties of the joint, thus promoting its premature
fracture in the zone of mixing of the base and electrode
material and along the fusion line. Repeated repairs
of these regions in case parts with austenitic electrodes
are accompanied by new failures, and increase the
scope of repair work.
Application of pearlitic electrodes by the recommended technologies [1, 4, 5] in combination with
preheating and post-weld heating of repair welding
regions ensures the required composition and necessary
level of mechanical properties of the deposited metal,
close to those of base metal, thus promoting a higher
quality of repair and extension of residual life of repaired turbine parts.
PWI conducted a package of work to study the
possibility of application of repair welding of turbine
*
The article is based on the results of fulfilment of the NASU Complex Program «Problems of operating service life and safety of
structures, constructions and machines» (2006--2009).
© A.K. TSARYUK, V.D. IVANENKO, V.V. VOLKOV, S.I. MAZUR, A.A. TROJNYAK, A.V. VAVILOV, A.G. KANTOR and N.P. VOLICHENKO, 2009
32
12/2009
Composition of 15Kh1M1FL steel, wt.%
15Kh1M1FL steel
C
Si
Mn
Cr
Mo
V
S
P
Not more than
Acc. to TU 108.671--77
Studied melt
0.14--0.20
0.2--0.4
0.6--0.9
1.2--1.7
0.9--1.2
0.25--0.40
0.025
0.025
0.16
0.28
0.55
1.3
1.0
0.30
0.003
0.003
case parts from cast chromium-nickel steels without subsequent heat treatment. Variant of repair welding of
widely applied cast heat-resistant steel 15Kh1M1FL
with pearlitic electrodes was taken as the basic one.
Composition of this steel is given in the Table.
Requirements to mechanical properties of castings
from 15Kh1M1FL steel (to TU 108.671--77) are as
follows: σm = 350 MPa; σt = 550--600 MPa; δ = 22 %;
ψ = 69 %; KCU = 40 J/cm2.
Repair welding technology should envisage measures preventing cold cracking in welded joints. Crack
resistance of welded joints can be ensured by selection
of thermal modes and conditions of welding, under
which the cooling rate will promote formation of HAZ
metal structure not prone to cracking. Therefore, the
influence of the thermal cycle of welding on the structure and properties of cast casing steel 15Kh1M1FL
was studied first of all. In keeping with the plotted
thermokinetic diagram of austenite transformation in
this steel (Figure 1) under different conditions of heating and cooling, characteristic for different welding
conditions, in the range of cooling rates of 0.33 to
25 °C/s at 500 °C the temperature of the end of
martensite transformation is above 290 °C, and hardness of structural components is on the level of
HV 180--340. At increase of cooling rate above
25 °C/s, steel structure is martensitic (Figure 2).
Hardness rises and at 100 °C/s is reaches HV 390--420.
It is known [6--8] that after completion of martensite
transformation below 290 °C and at more than 50 %
martensite content, there is a risk of cold cracking.
Therefore, in welding of such steel it becomes necessary to apply additional measures to adjust the process
of cooling of the welding zone in the form of preheating
and concurrent heating or application of welding processes providing joint self-heating.
In keeping with works [1, 3, 4] electrodes of E06Kh1M type (GOST 9467--75) are recommended for
repair welding without postweld heat treatment of
steels of the type of 15Kh1M1FL, 20KhMFL and
20KhML.
Metal deposited with electrodes of grade TML-5
(E-06Kh1M type) in as-welded condition has the following composition, wt.%: 0.044 C; 0.25 Si; 0.56 Mn;
0.69 Cr; 0.51 Mo; 0.021 P; 0.017 S. Mechanical properties of deposited metal at 20 °C: σt = 600 MPa; δ =
= 26 %; KCU = 173 J/cm2.
In order to asses cold cracking resistance of
15Kh1M1FL steel and determine the required temperature of preheating in repair welding investigations
were conducted by the Implant method [9], as well
as using Tekken and Lehigh University samples [10].
12/2009
Maximum (critical) stresses in the samples before
the start of fracture were taken as the criterion of
crack resistance of the welded joint in Implant testing.
Samples withstood the load for up to 24 h. During
testing beads were deposited by manual arc welding
with 4 mm electrodes of TML-5 grade at Iw = 175 A.
Bead length was 70 mm, deposition time was 30 ± 2 s.
Deposition was performed directly in the unit under
the conditions both without preheating and with preheating up to 250 °C.
Experimental data showed that cold cracking by
the delayed fracture mechanism (incubation period,
period of stable increase of microplastic deformations
and accelerated fracture period at critical stresses)
and, probably, formation of an unfavourable structure
in the deposition zone occur in welding steels of
15Kh1M1FL type (Figure 3, a). Application of preheating up to 200 °C allowed raising the level of critical stresses to 0.70--0.75 of base metal yield point
(Figure 3, b). Preheating promotes lowering of the
cooling rate at structural transformations, is favourable for the mode of microplastic deformation development and removal of diffusible hydrogen.
Technological samples for assessment of crack resistance were made of cast steel 15Kh1M1FL 20 mm
thick. Manual arc welding was performed with TML-5
and UONI-13/45A electrodes in the mode of Iw =
= 170--180 A with reverse polarity current. Applica-
Figure 1. Thermokinetic diagram of austenite transformation in
heat-resistant steel 15Kh1M1FL
33
Figure 2. Microstructure (×300) of 15Kh1M1FL steel in as-welded condition (a) and at w0 = 0.3 (b), 1.6 (c) and 100 (d) °C/s
tion of UONI-13/45 electrodes is necessary to create
«soft interlayers» at multilayer welding up of defects
or for coating the cut-out recess edges.
As shown by the results of the conducted technological sample testing, ensuring the crack resistance
in welding cast steel 15Kh1M1FL with electrodes of
E-06Kh1M type requires application of preheating up
to 200--250 °C.
It is known [11] that properties of the metal of
the weld and HAZ of welded joints of heat-resistant
steels depend to a great extent on their ambient temperature conditions immediately after the completion
of the welding process. Post-weld recovery is particularly effective for improvement of the ductile proper-
Figure 3. Deformation kinetics at Implant testing of 15Kh1M1FL
steel: a ---- without preheating; 1 ---- critical stress 300; 2 ---- 280;
3 ---- 240; 4 ---- 220 MPa; b ---- preheating to 200 °C; 1 ---- 350;
2 ---- 300 MPa
34
ties and crack resistance of welded joints [12, 13]. No
phase transformations are observed here, but favourable conditions are in place for removal of diffusible
hydrogen from the welding zone.
It should be noted that post-weld recovery, compared to high annealing, does not lower the level of
residual welding stresses. Now, relaxation of residual
stresses at service temperature is small. Therefore, the
repaired parts of the turbo units have a limited service
life (up to the next planned maintenance). After conducting the next examination and technical diagnostics a decision is taken on their further operation in
production.
Proceeding from the gained experience [13] it is
shown that application of recovery at temperature exceeding the cold brittleness range of metal of a specific
steel grade is the most effective to improve the welded
joint crack resistance. Proceeding from this principle,
the temperature of recovery of welded joints of
15Kh1M1FL type steel can be set on the level of
250--280 °C.
Conducted studies of the main technological characteristics of weldability of heat-resistant steels for
turbine case parts based on 15Kh1M1FL cast steel
with application of electrodes of E-06Kh1M type allow confirming the recommendations of [4] on the
possibility of repairing defects in cast case parts using
pearlitic electrodes. Post-weld heating in the form of
thermal recovery is also necessary for stabilization of
metal structure in the repair welding zone, acceleration of diffusible hydrogen evolution and prevention
of cracking after welding [11, 13].
To assess self-heating in repair welding of case
parts without preheating and post-weld heat treatment, «cross-hill» welding technique was tried [14],
12/2009
which owing to continuous deposition of welding
beads over the entire section of cut-out defect recesses,
ensures self-heating and allows repair welding to be
performed without preheating. Recesses can be welded
up in the downhand, horizontal and vertical positions.
To determine cold cracking resistance of the joints
in welding up case part damage by «cross-hill» technique, welding up of cruciform cut-out recesses was
performed. Two recesses normal to each other, each
of 50 mm length, 30 mm width, and 40 mm depth
were cut out in 60 mm plate of 15Kh1M1FL cast steel.
Welding was performed without preheating or postweld heating both with edge coating before welding
with UONI-13/45 electrodes and without coating
(Figure 4, a). Recesses were filled with 4 mm TML-5
electrodes, at Iw = 180 A in both the cases. Welding
was started from recess edges.
After welding the samples were cut into templates
to detect cracks and other defects, as well as study
the microstructure. As is seen from macrosections
shown in Figure 4, b--d, the appearance of the metal
of the weld and HAZ is typical for joints made by the
regular multilayer welding. Deposited metal is tight,
without pores, cracks, slag inclusions or other defects.
Obtained results allows considering the «cross-hill»
welding technique as one of the possible variants at
elimination of damage in cast case parts from heat-resistant steels without application of preheating or
post-weld heating.
Results of the conducted investigations allowed
considering the possibility of repair welding performance without subsequent heat treatment in welding
up damage on turbine case parts under stationary conditions. The selected object of application of the proposed repair welding technology was the cover of HPC
case of K-300-240 steam turbine from heat-resistant
cast steel 20KhMFL. HPC was examined during overhauling of unit #3 at Tripolskaya TPP. Visual-optical
examination (VOE) revealed non-through thickness
cracks with minimum opening on the inner surface of
outer cover of HPC case (Figure 5) in the region of
a jaw for key connection. The turbine had been in
operation for 248,667 h. Steam working parameters
were as follows: temperature of 545 °C, pressure of
245 atm. In order to take a technical decision on the
possibility of conducting repair welding without subsequent heat treatment the proposed technology was
first certified under TPP conditions. Certification
testing was conducted on a sample of 20KhMFL cast
steel of 500 × 300 × 60 mm size. Recess in the sample
simulated a non-through thickness crack 200 mm long
and 30 mm deep. Composition of metal of 20KhMFL
steel sample was as follows, wt.%: 0.20 C; 0.30 Si;
Figure 4. Macrosections of welded up cruciform recesses on
15Kh1M1F steel: a ---- longitudinal; b--d ---- cross-sections at the
start, middle and end of recesses, respectively
Figure 5. General view of inner surface of K-300-240 turbine HPC
case cover (arrow shows key connection, near which cracked sections
were found)
12/2009
35
Figure 6. Layout of crack cut-put recesses on inner surface of K300-240 turbine HPC case cover: h ---- recess depth
0.70 Mn; 1.10 Cr; 0.60 Mo; 0.25 V; 0.25 Ni; 0.28 Cu;
0.02 S; 0.02 P.
During certification testing the modes and technology of repair welding were optimized; non-destructive and destructive quality control of the welded
joint was conducted by the proposed technology;
physico-mechanical properties and structure of the
made welded joint and their compliance with the code
requirements were studied.
Certification testing was conducted by a program
developed at PWI, which took into account all the
requirements to repair welding of steam turbine cast
case parts [4].
Recess welding up was performed with 4 mm TML5 electrodes. Prior to welding electrodes were baked
at 400 °C for 2 h.
Plate preheating was conducted up to 250 °C in
the following modes: recess coating at Iw = 140--170 A;
recess filling (except for its middle part) at Iw = 160-180 A; recess middle part Iw = 140--170 A.
Complete filling of the recess was followed by
heating by thermal recovery mode at the temperature
of 250 °C with 15 h soaking. When recovery period
was over, the joint was cooled down at the rate of
about 50 °C/min up to plate temperature lowering
to 80 °C.
Welded joint quality was assessed by visual inspection (Section 16.3 RTM-1s--89), magnetic particle
testing (GOST 21105--87), as well as ultrasonic testing (Section 16.5 RTM-1s--89). Performed quality
control of the welded joint did not reveal any deviations from code requirements.
Investigations of mechanical properties showed
that welded joint ultimate strength in tensile testing
of samples is in the range of 530--560 MPa, and deposited metal impact toughness is equal to 148-170 J/cm2, which corresponds to requirements to this
steel (σt = 500 MPa and an = 50 J/cm2, respectively).
Metallographic examination of macro- and microstructure was conducted. Investigations showed absence of deffects in the weld and HAZ metal. Weld
metal hardness was HB 184, HAZ metal ---- HB 172
against HB 104--223 admissible for 20KhMFL steel
and HB 150--240 admissible for weld metal.
36
Thus, conducted testing of repair welding up of
an artificial defect on a plate from 20KhMFL steel by
the developed technology in keeping with the certification testing program, showed positive results. This
allowed taking a technical decision and recommending
this technology for repair welding of K-300-240 turbine HPC cover from cast steel of 20KhMFL type.
Welding technology was developed and technological
instructions were prepared on repair welding of HPC
case cover. Cracks were cut out with a pneumatic
chipper and abrasive tools with periodical surface inspections. Recess layout and their final dimensions
are given in Figure 6. After crack cutting-out the
surface was hogged and controlled by VOE and dye
penetrant testing. Control results were satisfactory.
Welding up and subsequent thermal recovery of
welded-up locations were conducted by the developed
technological process of repair welding. Non-destructive testing of repaired sections demonstrated the high
quality of the made welded joints. Block #3 with
K-300-240 turbine was accepted for further operation.
CONCLUSIONS
1. Weldability of typical cast heat-resistant
15Kh1M1FL steel was studied. This steel is widely
used in fabrication of casing equipment of turbo units
and high-pressure steam-water fittings.
2. It is shown that in repair welding of turbine case
parts thermal recovery can be used for welded joints
made with pearlitic electrodes with preheating and concurrent heating, instead of post-weld heat treatment.
3. Technology of welding envisaging application
of preheating and concurrent heating with subsequent
thermal recovery is proposed for repair of damaged
components of case equipment of turbo units from cast
heat-resistant steels. Service life of repaired turbo
units can be extended for an unlimited period.
1. Khromchenko, F.A. (2005) Welding technologies in repair
works. Moscow: Intermet Engineering.
2. Anokhov, A.E., Korolkov, P.M. (2006) Welding and heat
treatment in power engineering. Kiev: Ekotekhnologiya.
3. Anokhov, A.E., Khromchenko, F.A., Fedina, I.V. (1986)
New technology of repair welding without heat treatment of
chrome-molybdenum steel cast parts. Svarochn. Proizvodstvo, 10, 15--17.
4. (1988) RD 108.021.112--88: Repair of defects in cast casing
parts of turbine and fittings by repair welding without heat
treatment. Moscow.
5. Anokhov, A.E., Ganiev, F.B., Korolkov, P.M. (2003) Improvement of technology of repair welding and heat treatment as the base for prolongation of service life of steam
turbines. Montazhn. i Spets. Raboty v Stroitelstve, 7, 7--11.
6. Makarov, E.L. (1981) Cold cracks in welding of alloy
steels. Moscow: Mashinostroenie.
7. Hrivnak, I. (1984) Weldability of steels. Moscow: Mashinostroenie.
8. Shorshorov, M.Kh., Chernysheva, T.A., Krasovsky, A.I.
(1972) Weldability testing of metals. Moscow: Metallurgiya.
9. Kasatkin, B.S., Brednev, V.I., Volkov, V.V. (1981) Procedure of investigation of deformation kinetics in delayed fracture. Avtomatich. Svarka, 11, 1--3.
10. Kasatkin, B.S., Musiyachenko, V.F. (1970) High-strength
low-alloy steels for welded structures. Kiev: Tekhnika.
11. Kozlov, R.A. (1969) Hydrogen in welding of hull steels.
Leningrad: Sudostroenie.
12. Shorshorov, M.Kh., Belov, V.V. (1972) Phase transformations and change of steel properties in welding. Moscow:
Nauka.
13. Kozlov, R.A. (1986) Welding of heat-resistant steels. Leningrad: Mashinostroenie.
14. Sinadsky, S.E. Method of multipass welding. USSR
author’s cert. 202383. Int. Cl. B 23 K 9/00. Publ.
4.09.1967.
12/2009
ELECTRICAL CONDUCTIVITY OF SLAG POOL
IN ELECTROSLAG WELDING WITH WIRE ELECTRODE
Yu.N. LANKIN and L.F. SUSHY
E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
Equations and dependencies of electrical conductivity of the slag pool on immersion and position of wire electrode in
electroslag welding are given. Results of modeling slag pool conductivity using an electrolytic bath are presented.
K e y w o r d s : electroslag welding, slag pool electrical conductivity, wire electrode, simulation, electrolytic bath
Specific resistance of molten slag is several orders of
magnitude higher than that of current conducting cables and metal being welded. Therefore, slag pool
resistance Rsl largely determines the value of welding
current and, therefore, the process of electrode melting
and its stability.
To determine the regularities of variation of slag
pool resistance in electroslag remelting (ESR), potential distribution in electrolyte placed in a measuring
glass with mercury electrode on the bottom was studied in study [1]. A coated platinum electrode was
immersed into the electrolyte. Obtained results were
described by the non-linear equation
S
R = C  2
D 
 S α
 
d
 p γ
 ,
d
(1)
where R is the impedance; S is the interelectrode gap;
D is the measuring glass inner diameter; d is the electrode diameter; p is the electrode immersion; C, α, γ
are the constants non-linearly dependent on the coefficient of filling, the value of which is equal to 1.07 ≤
≤ D/d ≤ 6/6.
Dependence (1) is valid for ESR with an insulated
mould. In simulation of electroslag welding (ESW)
the measuring glass should be metallic. Therefore,
formula (1) can be used for ESW only as a variant
of the dependence of slag pool resistance on its parameters.
In [2] slag pool resistance is presented in the form
of two resistances connected in parallel: between the
immersed part of the electrode and mould wall R1,
as well as between the electrode tip and ingot pool
surface R2. These resistances are described by the
following equations:
R1 =
ρL
;
H
R2 =
ρl
.
 (C1 + C2)  

AL

 D -
2
B


(2)
Here ρ is the slag specific resistance, Ohm⋅cm; L is
the interelectrode gap, cm; A is the ingot cross-section,
cm2; l is the distance between the electrode and mould,
cm; C1, C2 is the circumference of electrode and mould,
© Yu.N. LANKIN and L.F. SUSHY, 2009
12/2009
respectively, cm; B is the area of circular clearance
between the electrode and mould, cm2.
Authors of [2] believe that the described model
provides a sufficiently accurate approximation of the
influence of various parameters of ESR process on slag
pool resistance characteristics.
Formulae (2) were derived for a round mould, and
equations (1) imply a non current-conducting mould.
In ESW slag pool of depth hs is in a rectangular
«mould» of width ba (corresponds to welding gap
width) and length which corresponds to thickness of
parts being welded. Below we will consider not the
slag pool resistance, but the inverse value ---- electrical
conductivity, as in this case the analytical dependencies are simpler. Electrical conductivity of the slag
pool between the lowered into it to the immersion
depth (immersion) electrode Ls into the slag and the
electrically conducting slag pool walls can be presented as a sum of electrical conductivities between
the electrode and each wall:
G=
1
=
R
5
∑ Gi.
i=1
In the first approximation the wall length was
taken to be unlimited. To calculate the slag pool conductivity between the electrode and one of the vertical
walls, let us use the formula for capacitance of single-wire line and ground per a unit of length, replacing
in it medium permittivity εa by slag pool electrical
conductivity average over the pool volume γs [3]:
G′i =
2πγs
 Hi + √

H2i -- r2 

ln 
r


,
where Hi is the distance from electrode center to i-th
wall of the slag pool; r is the electrode radius; H3 =
= ba -- H1; H4 = S -- H2. For an electrode immersed
into the slag to depth ls, we obtain electrical conductivity Gi = lsG′i.
To calculate slag pool electrical conductivity between the electrode and metal pool G5, let us use the
transformed formula for capacitance of two finite cylinders [4]:
37
Figure 1. Dependence of slag pool electrical conductivity on electrode immersion into it: 1 ---- slag pool admittance G; 2 ---- slag
pool conductivity at insulated shoes G1 + G3 + G5; 3 ---- conductivity
of the section electrode--molten metal pool G5; 4 ---- conductivity
of the section electrode--edges of parts being welded G1 + G4; 5 ---conductivity of electrode--shoe section G2 + G3

 4hs  ls 
2r
r2

 + .
G5 = 2πγs 
+ π ln 

 2(hs -- ls)
 hs -- ls  2 




Figure 1 gives the dependence of slag pool electrical conductivity on electrode immersion under the following conditions: slag pool depth hs = 50 mm; gap
ba = 30 mm; welded part thickness ---- 40 mm; electrode
diameter 2r = 4 mm; electrode is in the slag pool center
(H1 = H3 = 15 mm; H2 = H4 = 20 mm). One can see
from the Figure that the slag pool electrical conductivity in wire electrode welding rises practically linearly with increase of electrode immersion. Contribution of each of the three components of electrical conductivity (electrode--item edges, electrode--shoes,
electrode--metal pool) is approximately the same.
Dependence of slag pool electrical conductivity on
electrode position relative to edges of item being
welded is shown in Figure 2. Electrode immersion ls =
= 25 mm is taken in calculations.
It should be noted that the value of electrical conductivity of electrode--shoe section is somewhat higher.
As the heat conductivity of copper shoes is high and
they are intensively cooled by water, molten slag near
the shoe surface has a lower temperature compared to
pool average temperature. Influence of temperature Tsl
on specific electrical conductivity of liquid slag γs is
described by the following equation [1]:
γs = γ0 exp (--c/Tsl),
where γ0, c are the constants for this slag. According
to [5], electrical conductivity of popular flux AN-8
varies from 0 (at 950 °C) up to 4 Ohm--1⋅cm--1 (at
2000 °C). Thus, electrical conductivity of slag decreases at temperature lowering, and a layer of slag
of a lower electrical conductivity forms near the shoe
surface. Solidified slag (skull) can in principle be
regarded as non-conducting. In calculations electrical
conductivity of this layer is included in parallel to G4
and G5, reducing the resultant electrical conductivity
right down to zero. Unfortunately, there is a lack of
theoretical or experimental estimates of boundary
layer conductivity. Therefore, the total electrical conductivity of the slag pool is somewhere between G è
38
Figure 2. Dependence of slag pool electrical conductivity on distance H between electrode and closest edge of part being welded:
1, 2 ---- see Figure 1
G1 + G3 + G5. However, dependence of electrical
conductivity of the slag pool on electrode immersion
and position relative to the edges of parts being welded
qualitatively remains approximately the same.
To check the derived dependencies, simulation was
performed on an electrolytic bath. Bath and electrode
dimensions were taken to be the same as in calculations. Water was used as the electrolyte. The bath
was made from copper foil, and the electrode was from
steel wire. As electrical conductivity of water is several
orders of magnitude lower than that of metals, selection of the kind of metal for the model of the pool
and electrode is not important. To avoid electrolytic
phenomena the model was powered by alternating current of 1 kHz frequency. In Figures 1 and 2 points
indicate simulation results after scaling for comparison
with the calculated curves, and the presented data are
in quite satisfactory agreement. Some discrepancies
observed at slight immersion of the electrode (see Figure 1), are attributable to the influence of the meniscus due to electrode wetting.
In view of small scope of studies and lack of valid
data, the near-electrode processes on metal--slag
boundary were neglected in this work [5, 6]. Allowing
for the anode and cathode voltage drop does not qualitatively change the dependence of the slag pool impedance on different parameters of ESW process, determination of which is the main purpose of this study.
Thus, it was determined that in ESW with wire
electrode the slag pool electrical conductivity is directly proportional to electrode immersion. It almost
does not change, if the electrode is located at a distance
from the welded part wall greater than its diameter.
1. Omura, G., Vakabayashi, M., Hosoda, T. (1973) Analysis
of heat transfer during ESW. In: Electroslag Remelting:
Proc. of 2nd Int. Symp. on Electroslag Technology. Kiev:
Naukova Dumka, 180--202.
2. Tommanni, Zh.V., Kraj, D.A. (1973) Mathematical model
of ESW at direct current. Ibid., 221--231.
3. Govorkov, V.A. (1968) Electric and magnetic fields. Moscow: Energiya.
4. Glikman, I.Ya., Rusin, Yu.S. (1976) Calculation of circuit
element characteristics of radioelectronic circuits. Moscow:
Sov. Radio.
5. (1980) Electroslag welding and cladding. Ed. by B.E. Paton. Moscow: Mashinostroenie.
6. Mitchell, A. (1971) Mechanism of heat evolution and conduction during ESW. In: Electroslag Remelting: Proc. of
2nd Int. Symp. on Electroslag Technology. Moscow: Metallurgiya, 80--92.
12/2009
NEWS
«MAGNIT» ---- PORTABLE MACHINE
FOR CURVILINEAR LAYOUT OF ROLLED METAL
«Faktor Ltd.» (Moscow) mastered the production of
portable copying machines «Magnit», designed for
cutout of parts of sheet rolled metal using a magnetic
copying device. The machine represents a guide along
which the carriage is moved with a traverse mounted
perpendicularly on it. The rotation moment is transmitted to a magnetic finger which runs around the
preset contour templet. On the opposite end of the
traverse the cutters are fixed. The machine can be
equipped with any device for air plasma cutting of
metals of the grade PURM, and also with the equipment for gas-oxygen cutting. The machine is manufactured on the modern level using the best models of
driving equipment.
It has a number of considerable advantages as compared to the famous machines ASSh-2, ASSh-70,
«Ogonyok» and «Strela», such as: mobility; high accuracy of reproduction of preset contour due to rigidity
of the design; high speed of cutter travel (from 50 to
6000 mm/min); travel smoothness; high reliability
of the units owing to use of modern element base and
drives of the leading world manufacturers.
GAS-FLAME MACHINE FOR THERMAL SPRAYING OF POWDERS
«Technologic Centre «Tekhnikord Ltd.» offers a gasflame powder thermal spraying machine MRK-10 for
thermal spraying of powders of metals and alloys to
deposit coatings for protection of surfaces of parts
from different kinds of wear, cavitation, oxidation,
fretting corrosion, corrosion in aggressive media, and
also restoration of worn-out parts with simultaneous
improvement of their service properties.
The machine MRK-10 includes a powder gunsprayer PR-10 1 and control panel PU-03 2 for control
of working gases, which is mounted on the post 3.
There is a fixture for mounting of hopper 4, a powder
proportioning device, on a gun-sprayer. The gunsprayer is connected to a panel of working gases control through protective valves-flame extinguishers 5
by rubberized fabric hoses 6 with connectors for oxygen, combustible gas (acetylene, propane or MAF gas)
and compressed air.
The oxygen and combustible gas are supplied by
the hoses to the control panel from standard gas cylinders equipped with reducers. The compressed air,
supplied from the compressor, is preliminary purified
from the traces of oil and moisture, and then it is
supplied by the hose to the input of the unit of air
preparation of gas control panel.
12/2009
The design of gas control panel allows its use for
the work with gas-flame gun-sprayers of any companies. The machine can operate under shop or field
conditions in environments, not containing vapors of
acids, alkaline and other caustic liquids.
39
INTERNATIONAL CONFERENCE
«IMPROVEMENT OF TURBINE PLANTS
USING METHODS OF MATHEMATIC
AND PHYSIC MODELLING»
On 21--25 September, 2009 the Scientific-Technical
Conference «Improvement of Turbine Plants Using
Methods of mathematic and Physic Modelling» took
place at the territory of Zmievskaya thermoelectric
power station. The organizers of the Conference were
the National Academy of Sciences of Ukraine, A.N.
Podgorny Institute of Mechanical Engineering Problems of NASU, Ministry of Fuel and Energy of
Ukraine, OJSC «Turboatom», Company «Energoprogress», Ukranian Engineering-Pedagogical Academy,
Zmievskaya thermoelectric power station.
In the work of the Conference over 150 specialists
of 27 organizations and enterprises of fuel-power engineering complexes, research institutes, design bureaus, universities and academies of Ukraine, Russia,
Denmark, Poland and other countries took part. As
compared with the previous conference the growth of
representation of leading research institutes, thermoelectric power stations and higher educational establishments, in particular the E.O. Paton Electric Welding Institute, SPA TsKTI (Russia), IMS PAN (Poland), etc. was noted.
Prof. A.I. Shubenko, the deputy chairman of the
Organizing Committee, opened the Conference and
made a welcome speech. He greeted the participants
of the Conference with the beginning of its work and
also wished everybody successful and fruitful activity
and new beneficial cooperation. Further, he emphasized the importance of the problem of wear of turbine
plants and other equipment of thermoelectric power
stations and also peculiarities of its modernizing. The
reporter grounded the need in making the diagnostics
more precise, and also in subsequent replacement of
welded joints, as the most worn-out elements of power
equipment.
Then V.E. Levchenko, the director of Zmievskaya
thermoelectric power station, delivered a welcome
speech, describing briefly the condition of power
equipment of this thermoelectric power station and
tasks connected with its modernizing.
The Conference included the works of seven sessions: improvement of thermodynamic and ecological
characteristics of thermal turbine plants; improvement
40
of gas-dynamic processes and running parts of turbomachines; diagnostics, prediction, safety of operation
and residual life of turbine plants; problems of modernization and technical re-equipment of thermoelectric power plants; processes and structures of hydraulic turbines; problems of updating of designs and problems of energy-saving in gas-pumping equipment of
gas transport systems. In total, 5 plenary and 117
session reports were presented. The results of applied
investigations and practical developments devoted to
power equipment were reported. About a quarter of
reports included materials devoted to study of structure, properties, and also damage of welded joints
subjected to long-term service under the conditions
of fatigue and creep.
A number of reports caused active discussions, for
example, on the evaluation of crack resistance of rotors
of turbine K-1000-60/1500 of nuclear power station
and evaluation of residual life of elements of power
equipment, on the criterion of crack resistance.
The distinctive feature of the Conference, as compared with the previous one, was the participation of
significant amount of scientists from the higher educational establishments, and also young scientists and
post-graduate students in its work. The exchange of
results of developments on the problem of modernization of uniform equipment of thermoelectric power
stations between specialists of Ukraine, CIS and other
countries was also quite beneficial.
The resolution, including recommendations and
proposals to the governing bodies of Ministry of Fuel
and Energy of Ukraine, State Nuclear Power Complex
and thermoelectric power stations was adopted at the
Conference.
In general, the Conference promoted the beneficial
exchange of information of scientists working in the
field of diagnostics of condition, determination of residual life and modernization of equipment of thermoelectric power station.
Prof. V.V. Dmitrik,
Ukranian Engineering-Pedagogical Academy
12/2009
SEMINAR ON WELDING TECHNOLOGIES
«FULL READINESS TO EXCELENT WELDING OF STEEL»
On October 29, 2009 in Knyazhichi village (Kiev region) a one-day seminar on welding technologies on
the subject «Full Readiness to Excellent Welding of
Steel» took place at the Technological Center of
«Fronius Ukraina Ltd.». The representatives from a
number of enterprises of different branches of industry
of Ukraine, in total over 30 experts, participated
there.
The program of seminar, held in the form of dialogue between managers of «Fronius Ukraina Ltd.»
and its participants, included theoretical and demonstration parts on the following subjects:
• New generation of equipment Trans Steel
3500/5000 for welding of steel;
• PCS ---- powerful welding of steel using a pulsed
arc;
• New welding trolleys FDV 15/22 MF.
V.L. Bondarenko, the marketing director of
«Fronius Ukraina Ltd.», described briefly the basic
areas of activity of main company «Fronius» (Austria)
including development and manufacture of welding
machinery (main division of the Company), startingcharging devices and also equipment on convertion of
solar energy (capacity of up to 4 kW).
The production of welding equipment (concentrated in Austria, Chech Republic and Ukraine) includes equipment for manual arc welding,
MIG/MAG processes, TIG and plasma welding. The
Company offers also the system solutions on automation of welding processes. In this case the welding
equipment is completed with tables, roller supports,
trolleys. There is a department, specialized on development and production of equipment for orbit welding. In the last years the activity of Company in the
field of development and manufacture of equipment,
accumulating and transforming the solar energy into
domestic electric power, has been recognized highly
by many European societies.
In Donetsk and stry (Lvov region) the affiliates
of «Fronius Ukraina Ltd.» were created. In Kiev the
activity of Technologic Centre has lived up. Its task
12/2009
is to help the potential customer to choose optimal
technological joining process, to select the appropriate
equipment, to set-up it at the manufacturing facility,
to train workers-welders, to test reference specimens
of welded joints.
V.L. Bondarenko told about exposition of
«Fronius» at the recent exhibition this year in Essen.
At the area of 2000 m2 17 exhibits were placed among
which «Trans Steel», the system for high-quality
welding; CMT, the prospects of cold metal transfer;
«Virtual Welding», the training system which saves
time and materials; «Autonomous Welding» (welding
without human interference, the latter observes welding process on the monitor); «New Contact Tip» increases life of current-carrying tip by seven times in
MIG/MAG welding; «Service of Welding Equipment», the guarantee period is prolonged up to seven
years; «Mechanisation and Automatisation of Welding Processes» ---- autonomous magnetic trolleys of
two types, systems of control of orbit welding, systems
of programming and data recording.
The reporter demonstrated the examples of automation of welding processes on the screen during performance of long longitudinal welds, welding of Tjoints, deposition of surfaces in the pipe of the depth
of up to 3 m and other.
The advantages of cold metal transfer (CMT) were
stipulated by different improvements with the aim of
widening the technological fields of application. It
can help for example in butt welding of two plates of
thickness of not more than 0.2 mm without backing
and with the highest quality. CMT is applied for the
so-called studding of parts of stainless steel, aluminium or structural low-carbon steel with further
deposition of a polymer layer. The deposited «studs»
of metal play role of a peculiar frame. This method
can be furtherly applied in producing of bimaterials,
for example, of thin sheet of metal with deposited
41
studs of the length of up to 5 mm and with a polymer
coating.
The theoretical part of the seminar was continued
by the speech of R. Kulish, the manager of «Fronius
Ukraina», who described the welding system «Trans
Steel 3500/5000» for MIG/MAG and manual arc
welding. The machines of this series (of 350 and
500 A) are equipped with a unique inverter developed
by the «Fronius» and providing some characteristics
of welding: standard, special ---- dynamic (to increase
penetration depth and welding speed) and also with
a thin soft arc for welding of a root weld or welding
in a wide gap. The machines are easy to control. They
have all markings, such as directions to a welder for
the start of the work and only two handles to control
current and voltage. In manual welding mode these
two parameters can be preset separately, and in the
mode «Synergic» they are correlated, thus providing
the maximum good results of welding.
The products of the series «Trans Steel» are easy
to control and provide high reliability plus perfect
welding characteristics. The central control unit is
responsible for stability of process and repeatability
of welding results even in the situation of changing
42
process conditions. The Steel Transfer Technology was
additionally improved in the first turn owing to innovation wire feed. Light strong unit, including a
circuit-package, torch and control display, guarantees
reliable welding filler wire feed. The function «Comfort wire» performs automatic wire loading. The user
can easily remove the wire feed portable unit and carry
it to hard-to-reach places of site area to perform welding. Irrespective of position of circuit-package the
welding parameters remain stable.
The innovation connector FSC (Fronius System
Connector) is designed for manual and robotic application, for systems with gas and water cooling, it
improves quality, reliability, versatility and comfort
of the work. Owing to central connector for all external devices, the user can refuse the external control
plugs. The ergonomic torch enables quick and reliable
replacement due to a lever lock.
The machines of series «Trans Steel» are suitable
for operation at a long period even at intensive use.
V. Slyuta, the head of department of equipment
and technologies of the Technological Center, described the development by «Fronius» of the process
of high-powerful pulsed-arc welding with a drop transfer using characteristic of pulse controlled-spray arc
(PCS). The characteristic PCS corresponds to welding
with a constricted arc. This process is transient between a pulsed-control and spray one. The arc in a
mixed mode is burning «buried» relative to a weld
12/2009
pool. The minimal light radiation is provided, the
increase in penetration depth even at increased welding speeds is achieved.
To realise welding process with PCS characteristic,
it is necessary to apply special high-capacity inverter
providing a pulsed process of arc burning.
In conclusion of theoretical part of Seminar the
presentation of versatile welding trolleys with a magnetic clamp FDF 15/22MF, ensuring accurate travel
of welding head at performance of welds in different
spatial positions using MIG/MAG methods, was
made. Unlike the trolleys applied formerly they do
not require guides, they do not have cable networks
and arranged directly on the workpiece, they are light,
the control is simpliest, the supply is from batteries.
The trolley has a unit for mounting of a manual torch.
The battery unit is also arranged on the trolley. The
completing of the trolley with a simple welding tractor
is possible. If necessary, the system of tracking the
butt and torch oscillation unit can be arranged on the
trolley. Additional equipment: charging device for the
battery and overcharged battery with capacity of
14.4 V/2 A⋅h.
In the second part of the Seminar the managers of
«Fronius Ukraina» demonstrated the operation of machine «Trans Steel 3500», the process CMT in the
robotic-technical complex, showed peculiarities of application of welding trolleys with a magnetic clamp.
Besides, the stand for demonstration of possibilities
of plasma welding, whose technology provides quality
welding of stainless steels of thicknesses from 0.2 up
to 12 mm of penetration for one pass was presented.
The sizes of workpieces are not limited here.
The participants of the seminar were invited for
the International Industrial Forum (Kiev, International Exhibition Center, 24--27.11.09) to the stand
12/2009
«Fronius Ukraina». A new complex «Virtual Welding» designed for training of welders will be presented
for the first time in CIS.
All participants expressed thanks to the organizers
of the seminar for informative program, possibility of
the detailed familiarization with advanced models of
equipment and technologies.
Prof. V.N. Lipodaev,
Dr. A.T. Zelnichenko, PWI
43
INTERNATIONAL EXHIBITION
«WELDEX/ROSSVARKA-2009»
The 9th International Exhibition «Weldex/Rossvarka-2009» took place in Moscow at International
Exhibition Center «Crocus Expo» in October 12--15,
2009. It was organized by Closed Joint Stock Company
«International Exhibition Company» with the assistance of Company «Elsvar» and support by the Chamber of Commerce and Industry of the Russian Federation, Russian Scientific and Technical Welding Society (RSTWS) and Moscow Inter-branch Association
of the Chief Welders.
More than 75 specialized firms, companies, institutes, small and medium businesses, trade organizations from nine countries (Great Britain, Germany,
China, Portugal, Russia, USA, Ukraine, Finland and
Switzerland) took part in the Exhibition. The Russian
exposition was the most representative (more than 60
booths). Among them were such famous manufacturers of welding equipment of Russia as ITS (St.-Petersburg), FSUE GRPZ (Ryazan), SPA «Plazma»
(Rostov-on-Don), CJSC PKTBA (Penza), Faktor
Ltd. (Moscow), Avtogenmash Ltd. (Tver), as well
manufacturers of welding consumables ---- OJSC
«Mezhgosmetiz-Mtsensk» (Orel), CJSC «Zapsibgazprom» (Tyumen).
Ukraine at the Exhibition was represented by the
E.O. Paton Electric Welding Institute, «Donmet»
enterprise (Kramatorsk), Ilnitsky Factory for Mechanized Welding Equipment, «Artyom-Kontakt» enterprise (Kiev), as well as journals «Avtomaticheskaya
Svarka» (Automatic welding) and «Svarshchik»
(Welder).
Noteworthy among the world brands that took part
in the Exhibition are the American Company «Mathey
Dearman» (equipment for construction and repair of
main pipelines), «Lincoln Electric» (equipment for
manual, arc, argon-arc and MIG welding, plasma cutting, automated and robotic systems, welding consumables for a wide range of applications, presented by
44
the Moscow branch), KEMPPI (high-tech welding
equipment for all arc processes, welding torches,
masks, accessories), «Linde Gas» (manufacture of a
whole range of welding gases and mixtures), ESAB
(materials and equipment for welding, Moscow
branch).
A number of the leading research, technical and
engineering centers of Russia, such as the Alliance of
the Saint-Petersburg and North-West Region Welders
(St.-Petersburg), «Progress» (Izhevsk), State Engineering Center (SEC, Moscow), Moscow InterBranch Association of the Chief Welders, also presented their expositions at the Exhibition.
Subjects of the Exhibition traditionally included
demonstration of the achievements in the field of modern technologies, equipment and materials applied in
welding, cutting, cladding, brazing and soldering,
heat treatment and coating; developments and productions of systems for ventilation, air conditioning,
means for welder and environment protection; and
production of specialized types of equipment and technologies. The tendency to a wider demonstration of
achievements in the field of automation and robotization of welding processes looked natural under the
conditions of the observed improvements of the economy in East-European countries. Together with a demonstration of robotics by the Moscow branch of
«KUKA Robotics», the booth of the «Kontur» Ltd.
(Moscow), dealing with design of blanking and welding shops for plants manufacturing metal structures,
and exhibiting the possibilities of a wide application
of robotic welding complexes and automated devices,
looked traditionally spectacular.
Among the novelties of the Exhibition was a line
of domestic technological universal robots of the TUR
series with a nominal carrying capacity of 15 up to
350 kg, developed by SEC, which was appointed in
2008 by the Government of the Russian Federation
12/2009
to be a head organization to ensure, together with
OJSC «Avtovaz», scientific and technical development of domestic machine-tool construction and technological re-equipment of strategic branches of machine building with preferential utilization of competitive technologies and equipment. All of these robots are universal industrial robots of the articulated
type, having six degrees of freedom and designed for
resistant, laser, arc and hybrid welding, laser and
plasma cutting, cutting with high pressure water, gluing and sealing, storage and transportation of freight.
At present, «Avtovaz» is active in preparation for
building of the facilities capable of manufacturing up
to 1000 such robots per year.
One-day international conferences «Automation and
Mechanization in Advanced Welding Technologies for
Application under Current Conditions in Leading
Branches of Industry, Power Engineering and Building»
(organizer ---- CJSC MVK, RSTWS and journal
«Svarochnoe Proizvodstvo» (Welding production)), as
well as scientific and practical conference on welding,
cutting, brazing, soldering and related technologies in
the form of a business club on professional interests
(organizers ---- CJSC MVK, Moscow Inter-Branch Association of the Chief Welders) took place during a
period of the Exhibition. Two papers covered the issues
of certification in welding engineering.
G. Fernandes, member of the Board of Directors
in the IIW, manager of the IIW Certification System,
in his paper «International System for Qualification
and Certification of Welding Staff and Institutions»
considered the main IIW documents regulating procedures of certification of the staff and institutions.
He noted that a special organization International
Authorized Board (IAB), dealing with qualification
and certification, was formed under the IIW. Also,
he marked that the National Agency of Control and
Welding is an authorized body for issuing certificates
in the field of welding in Russia.
O.A. Tsukurov (Center for Certification of Welding Facilities) presented paper «Problems of Keeping
to Technical Specifications for Welding Processes and
Ways of Their Solution». He noted that currently
there are no requirements in specifications to the weld-
12/2009
ing processes. Thus, the Committee on Technical
Regulation was formed (July 2009) under the auspices
of RSTWS to solve these problems. The Committee
will hold a range of seminars devoted to the issues of
technical regulation in the field of welding engineering in 2009--2010.
Presentations of the developments of such companies as KUKA Robotics, Scansonic (Germany), KEMPPI (Finland), Dukon, Svacha, SovPlim, Elsvar,
Tekhnikord (Russia) etc. were made at the other Conference.
It should be noted in conclusion that there were
much less exhibitors at this Exhibition than at the
previous ones. The same relates to the quantity of the
visitors. This corresponds to «InformExpo» agency
data, according to which the number of exhibitors in
whole for exhibitions in the first half of 2009 in Moscow reduced at an average by 20 %.
Next «Weldex/Rossvarka» Exhibition will be
held on its favorite site ---- in Sokolniki in 2010, which
suggests certain optimism in relation to further development of activities of the main Russian Exhibition
on welding and related technologies.
Dr. V.N. Lipodaev,
Dr. A.T. Zelnichenko, PWI
45
INTERNATIONAL SCIENTIFIC AND TECHNICAL
CONFERENCE «PROBLEMS OF WELDING, RELATED
PROCESSES AND TECHNOLOGIES»
The International Conference under the auspices of
Prof. B.E. Paton, President of the National Academy
of Sciences of Ukraine and Director of the E. O. Paton
Electric Welding Institute, took place at the Admiral
Makarov National Shipbuilding University (NSU) in
Nikolaev, October 14--17, 2009. It was dedicated to
the 50th anniversary of the Welding Engineering
Chair of NSU and 75th anniversary of the E.O. Paton
Electric Welding Institute of the NAS of Ukraine.
Scientists from Ukraine, Russia, Belarus, China, Poland and Vietnam, and representatives of more than
60 organizations and enterprises took part in the Conference. 130 papers on the relevant trends in welding
engineering, including 39 plenary papers, prepared by
the researchers of the E.O. Paton Electric Welding
Institute, I.N. Frantsevich Institute of Problems of
Materials Science (IPMS), Physical-and-Technological Institute of Metals and Alloys (PTIMA) of the
NAS of Ukraine; Institute of High-Current Electronics, Institute of Physics of Strength and Materials
Science, Institute of Theoretical and Applied Mechanics of the Siberian Division of the RAS; Belarusian
State University, B.I. Stepanov Institute of Physics
of the NASB, Belarusian State University of Informatics and Radioelectronics; Beijing Institute of Aeronautical Materials; K.E. Tsiolkovsky Russian State
Technological University (RGTU), Moscow Energy
University, Voronezh State Technical University,
NTUU «Kiev Polytechnic Institute», Admiral
Makarov NSU, I. Pulyuj Ternopol State Technical
University (TSTU), V. Dal East-Ukrainian National
University (EUNU), Priasovsky State Technical University (PSTU), P. Mogila Chernomorsky State University (ChSU), as well as OJSC «Vadan shipyards»-«Okean» and State Enterprise «Zoray-Mashproekt»,
were presented at the Conference.
Most of the papers (13) with diverse topics were
presented by the scientists of the E.O. Paton Electric
Welding Institute. Three papers by the PWI researchers were dedicated to new developments in the
field of welding consumables for shipbuilding and ship
repair (Prof. I.K. Pokhodnya et al.), three papers
were dedicated to materials weldability (Prof. V.I.
Makhnenko, Prof. M.M. Savitsky et al.), and two
papers ---- to brazing of materials (Prof. V.F. Khorunov et al.). The paper by Prof. I.V. Krivtsun was
dedicated to new developments in the field of hybrid
laser-plasma welding technologies and materials treatment. Other papers were dedicated to thermal spraying of coatings (Prof. Yu.S. Borisov), diffusion bonding of titanium structures (Prof. L.S. Kireev), mecha-
46
nized gas shielded welding of steel (Prof. I.P. Pentegov), and surface cleaning prior to welding and related
processes (Prof. A.A. Kajdalov).
Four papers, dedicated to utilization in welding
and related technologies of concentrated energy flows
(CEF), in particular, low-energy (20--30 kV) highcurrent (hundreds of amperes) electron beams
(HCEB) (Profs. N.N. Koval, V.E. Ovcharenko, O.P.
Solonenko, Yu.F. Ivanov et al. from the Siberian Division of the RAS) and compression plasma flows
(Profs. V.V. Uglov, V.M. Astashinsky, N.T. Kvasov,
N.N. Cherenda from Belarus), were presented. Application of HCEB for diffusion bonding and pressure
brazing was considered in papers presented by NTUU
«Kiev Polytechnic Institute», NSU, ChSU
(Prof. V.D. Kuznetsov, Dr. V.V. Kvasnitsky,
Profs. V.F. Kvasnitsky and L.M. Dykhta). The CEF
are used for modification and alloying of surfaces by
controlling structure, composition and properties of
materials. They are intensively developed now, and
earlier they belonged to double-application national
critical technologies.
The paper by Prof. A.N. Gedrovich and Dr. A.B.
Zhidkov (V. Dal EUNU) demonstrated new capabilities in improving the quality of welded structures by
vibration treatment. Peculiarities and prospects of
wear-resistant cladding by using flux-cored strip were
presented in the paper by Prof. V.V. Chigarev and
Dr. A.G. Belik (PSTU).
A range of papers was dedicated to the problems
occurring in operation of welded structures. The paper
by Prof. N.I. Pidgursky (TSTU) considered the
mechanisms of propagation of fatigue cracks.
Prof. V.I. Makhnenko and Dr. A.S. Milenin in their
paper proposed a method for ranking of defects in
main gas pipelines, based on the probabilistic evaluation of the risk of emergency situations and allowing
planning of repair without interruption of operation
of a main gas pipeline. Methods for calculation of
fatigue strength of welded ship hull structures, allowing for design and technological factors, were discussed in the paper by Prof. L.I. Korostylyov (NSU).
The papers presented at the Conference also considered manufacturing technologies for ship hull construction and ship machine building. The efficiency
of different methods for welding of erection joints on
the ship hulls was analyzed by Drs. N.P. Romanchuk,
S.V. Dragan, Yu.V. Solonichenko et al. («Vadan shipyards»--«Okean», NSU). The paper by Drs. V.V.
Romanov and Yu.V. Butenko («Zorya-Mashproekt»)
showed the role of modern welding and related tech-
12/2009
nologies in enabling development and manufacture of
different-application high-efficiency gas-turbine
units, competitive in the word market.
Weldability of heat-resistant cobalt alloys was
studied by researchers of PTIMA (Prof. V.M. Simanovsky et al.), and new power sources based on a
quasi-resonance transformer for plasma technologies
were discussed in the paper by the NSU researchers
(Dr. E.N. Vereshchago et al.).
The paper by Prof. R. Yastrzhebsky and associates
was dedicated to technologies for welding of aluminium
alloys, high-strength and stainless steels to fabricate
different-purpose structures. Prof. A. Klimpel and associates (Poland) considered repair laser welding of aircraft engine valves made from nickel alloy. Eng. V.P.
Slyuta (Fronius Ukraine, Ltd.) presented a new technology for electric arc welding of 0.3--3.0 mm thick
sheets with controlled metal transfer.
Ten papers presented at the plenary session were
devoted to solid state joining and brazing of materials.
In addition to the above paper by Profs. V.F. Khorunov (PWI), Yu.V. Najdich et al. (IPMS) proposed
a method for brazing of refractory metals and oxide
materials by using Ni--Nb, Cu--Ni--Nb and Au--Nb filler
alloys. Dr. S.V. Maksymova (PWI) suggested the
developed filler alloys and technology for brazing of
intermetallic titanium alloys. Filler alloys for joining
of materials based on Ti3Al intermetallic were discussed in the paper by Prof. X.P. Xing.
Solid state joining of dissimilar metals by passing
a high density current pulse was considered in the
paper by Prof. A.I. Vovchenko et al. (Institute for
Pulse Processes and Technologies). Prof. V. Mao et
al. (China) identified conditions for producing the
TLP-joints (diffusion bonding through a fused insert)
on single-crystal nickel superalloy DD6. The papers
by Profs. V.V. Peshkov and L.S. Kireev (Volgograd
State Technical University and E.O. Paton Electric
Welding Institute), V.D. Kuznetsov and Dr. V.V.
Kvasnitsky (NTUU «Kiev Polytechnic Institute»),
Drs. G.V. Ermolaev and A.V. Labartkava (NSU)
were devoted to improvement of the technologies for
diffusion bonding of dissimilar metals, based on investigation of thermal deformation processes and mod-
12/2009
elling of the stress-strain state in bonding and cooling
of the dissimilar joints with formation of residual
stresses. Unique items were produced by Prof. O.A.
Barabanova et al. (K.E. Tsiolkovsky RSTU) by using
diffusion bonding to manufacture a complex metalglass composite material with coagulation of copper
for reducing structural and thermal stresses.
The papers dedicated to the history of development
of the Welding Engineering Chair at NSU (Profs. S.S.
Ryzhkov, V.F. Kvasnitsky (NSU), V.M. Emelianov
(ChSU), as well as to the role of the E.O. Paton
Electric Welding Institute in progress in the field of
shipbuilding (Prof. A.N. Kornienko, Dr. A.P. Litvinov, and Prof. A.G. Potapievsky), were also presented
at the Conference.
The poster session was held on October 14, as well
as during the plenary session breaks on October 15
and 16, 2009. Subjects of the poster papers included
almost all the industrial sectors, fusion and pressure
welding methods, as well as related processes and
technologies.
The poster papers were presented by virtually all
chairs related to welding, which exist in Ukraine.
The plenary papers were published in the Transactions of NSU (2009, Nos. 3, 4), and the poster papers ---- in book «Problems of Welding, Related Processes and Technologies»: Proceedings of the International Scientific and Technical Conference Dedicated
to the 50th Anniversary of the Welding Engineering
Chair of NSU and 75th Anniversary of the E.O. Paton
Electric Welding Institute of the NAS of Ukraine.
A decision was made as a result of the Conference,
emphasising a high scientific level and practical importance of the presented papers and active participation of welding scientists and specialists in the corresponding research. It was decided to hold the Conference «Problems of Welding, Related Processes and
Technologies» on a regular, every two years basis.
Participants of the Conference visited OJSC
«Vadan shipyards»--«Okean» and State Enterprise
«Zoray-Mashproect» in Nikolaev.
Prof. V.F. Kvasnitsky, NTUU
47
INTERNATIONAL CONFERENCE «HIGH MAT TECH»
On October 19--23, 2009 the International ScientificTechnical Conference «High Mat Tech», devoted to
materials science problems, took place in Kiev at the
NTUU «Kiev Polytechnic Institute». The Conference
was organized by Ministry of Science and Education
of Ukraine, the National Academy of Sciences of
Ukraine (NASU), Ukrainian Materials Science Society (UMSS), NTUU «Kiev Polytechnic Institute»,
I.N. Frantsevich Institute of Problems of Materials
Science of NASU, «Intem Ltd.» (Ukraine). The informational partners of the Conference were journals
«Tekhnika Mashinostroeniya» (Machinery Engineering) (Russia), «Poroshkovaya Metallurgiya» (Powder Metallurgy) (Ukraine), «Nanostrukturnoe Materialovedenie» (Nanostructured Materials Science)
(Ukraine), «Deformatsiya i Razrushenie» (Deformation and Fracture) (Russia). The Conference took
place under the auspices of the Federation of European
Materials Science Societies, European Materials Science Society, Secretariat of European Association of
Powder Metallurgy (EUREKA), National Informational Centre on RP7.
In the work of the Conference about 170 scientists,
teachers, post-graduate students and engineers of the
leading research institutes, research centers, universities, academies and other organizations of 19 countries took part.
A.G. Kostornov, Prof. of NASU, opened the Conference and also delivered a welcome speech. He
wished all the participants successful work, business
cooperation, briefly reported on the tasks of the Conference and organizational matters.
The Conference included work of nine sessions:
metallic materials and technologies of their producing
and treatment; ceramics of functional and structural
purpose; surface engineering; modern technologies of
materials joining; powder metallurgy: state-of-the-art
of science and production; innovation materials based
on disperse particles (powders, fibers and other),
properties, technologies; fundamentals of modern materials science; diagrams of state, modeling of technologic processes of material production and properties
of modern materials; materials of medical purpose;
composite materials: special properties and prospects
of practical use; nanomaterials science: technologies
and materials.
48
The number of reports provoked active discussions
caused by great interest of the Conference participants
to the new scientific results in some scientific areas.
One of such areas was development of nanotechnologies and nanomaterials with improved service characteristics. In the development of this area, as followed
from the reports, the famous research centers of the
world took an active part: I.N. Frantsevich Institute
of Problems of Materials Science of NASU, E.O. Paton Electric Welding Institute, Institute fuer Metallkunde und Metallphysik PWTN (Germany), A.A.
Bajkov Institute of Metallurgy and Materials Science
of the RAS (Moscow, RF) and many other.
The interesting were the reports devoted to the
technologies of joining of materials, including also
welding technologies. For example, the interest was
shown to the report «Diffusion welding of refractory
metals and heat-resistant alloys» (OJSC «Ramenskoe
Instrument Engineering Design Bureau», RF), and
also to the report «Prospects of producing layer metal-ceramic materials using explosion welding» (Institute of Structural Macrokinetics and Problems of Materials Science of the RAS, RF).
In accordance with the program of the Conference
along with the session reports the poster reports were
also presented. In total, 220 reports and oral presentations were prepared.
The majority of information presented at the Conference proved the high scientific-technical level of
experimental works. The level of the Conference organization was also high. In the course of the Conference its participants exchanged information, discussed
the ways of further development of problems of materials science area, strengthened old and established
new business contacts, and also defined the ways of
performance of joint scientific programs. The prospects for the further scientific cooperation were also
outlined.
At the summing up of results the participants of
the Conference noted its actuality and usefulness for
the further development of materials science, including area connected with producing of new structural
materials using different welding processes.
Prof. V.V. Dmitrik,
Ukranian Engineering-Pedagogical Academy
12/2009
INDEX OF ARTICLES FOR TPWJ’2009, Nos. 1--12
Dear Readers
11
50 years of explosion welding
11
7
Paton B.E. 25 years of welding in open space
75th Anniversary of the E.O. Paton Electric Welding Institute
10
75 years of the E.O. Paton Electric Welding Institute of
the NAS of Ukraine
9
BRIEF INFORMATION
Application of protective extension in thermal spraying of
quasi-crystalline coatings (Murashov A.P., Demianov I.A.,
Grishchenko A.P., Burlachenko A.N. and Vigilyanskaya
N.V.)
4
Device for igniting arc of double-anode plasmatron
(Makarenko N.A., Chigarev V.V., Granovsky N.A., Bogutsky A.A. and Kushchy A.M.)
2
Effectiveness of application of algorithms for identification
of weld reinforcement in digital images (Lazorenko Ya.P.,
Kolyada V.O., Shapovalov E.V., Lutsenko N.F. and Skuba
T.G.)
7
Electrical conductivity of slag pool in electroslag welding
with wire electrode (Lankin Yu.N. and Sushy L.F.)
12
3
Equipment and consumables for hard-facing of lining plate
elements (Zhudra A.P., Voronchuk A.P. and Veliky S.I.)
6
Hard-facing bay for repair of hydropower equipment parts
in «Sakenergoremonti» company (Kuskov Yu.M., Ryabtsev I.A., Demchenko Yu.V., Denisen koA.M., Dzhavelidze Z.Z., Kbiltsetsklashvili Kh.N. and Khutsishvili
A.A.)
1
New books
1
New equipment for hard-facing of charging device bells and
cups (Zhudra A.P., Voronchuk A.P., Fomakin A.A. and
Veliky S.I.)
9
1--4, 10, 12
On the role of contact resistances in electroslag cladding
process (Tsykulenko K.A.)
2
Refined mathematical model of the electric arc burning in
plasmatron with external current-conducting wire (Kharlamov M.Yu., Krivtsun I.V., Korzhik V.N., Petrov S.V.
and Demianov A.I.)
1
Seam-tracking system in anticorrosion coating units
(Shapovalov E.V. and Kolyada V.A.)
5
Theoretical prediction of fatigue life of welded structures
at bifrequency spectrum of cyclic loading (Makhnenko V.I.
and Romanova I.Yu.)
Thesis for a scientific degree
12/2009
Experience of effective organisation of training of specialists of welding production for shipbuilding (Kostin A.M.)
8
Influence of the ratio of dimensions of cylindrical parts
from dissimilar materials on their stress-strain state in diffusion welding (Kvasnitsky V.F., Matvienko M.V., Ermolaev G.V., Labartkava A.V. and Kuznetsov V.D.)
8
Influence of welding and post-weld heating on structural
transformations and properties of HAZ of welded joints on
hardening steels (Lebedev Yu.M.)
8
Peculiarities of formation of stress-strain state in diffusion
bonds between dissimilar materials (Makhnenko V.I. and
Kvasnitsky V.V.)
8
Power supply systems based on resonance inverters (Vereshchago E.N. and Kostyuchenko V.I.)
8
Status of welding production at shipbuilding plants of
Ukraine (Kvasnitsky V.F., Bugaenko B.V., Goloborodko
Zh.G., Ilyushenko V.M., Romanchuk N.P., Solonichenko
Yu.V. and Shamraj A.N.)
8
Technology of automatic submerged-arc welding and cladding by low-density current (Dragan S.V., Yaros Yu.A.
and Yaros A.A.)
8
DEVELOPED at PWI
Electrohydraulic-pulsed treatment for strengthening the
surfaces of 110G13MLS steel frogs (Onatskaya N.A. and
Demidenko L.Yu.)
News
CHAIR OF WELDING ENGINEERING
OF THE ADMIRAL MAKAROV NATIONAL
SHIPBUILDING UNIVERSITY IS 50 YEARS
10
3, 8
1--6
INDUSTRIAL
Application of electron beam welding in the nuclear industry (Review) (Uratani Yo., Takano G., Nayama M. and
Shimokusu Yo.)
7
Application of emulsion explosives for explosion welding
(Silvestrov V.V., Plastinin A.V. and Rafejchik S.I.)
11
Application of laser-arc cladding for filling up narrow cavities in aluminium alloy items (Khaskin V.Yu.)
2
Application of plasma-arc metallisation for restoration of
wheel pairs (Zelenin V.I., Kavunenko P.M., Tisenkov
V.V., Teplyuk V.M., Poleshchuk M.A., Lebed V.D., Lipisy
V.I., Bondarev S.V., Gavrilov S.A., Olgard N.T. and Cheburov S.A.)
12
Arc spot welding of overlap joints in vertical position (Lobanov L.M., Timoshenko A.N. and Goncharov P.V.)
1
Bimetal steel-aluminium joints in shipbuilding hull structures (Oryshchenko A.S., Osokin E.P., Pavlova V.I. and
Zykov S.A.)
10
Comparative tests of welding-technological properties of
inverter and thyristor power sources (Ilyushenko V.M.,
Butakov G.A., Ganchuk A.V., Ostapchenko V.A. and Goryajnov N.A.)
4
Control of manipulation robot force action (Tsybulkin
G.A.)
4
Current status of welding consumables production in Russia
(Sidlin Z.A.)
2
Current status of welding fabrication in Japan (Bernadsky
V.N. and Makovetskaya O.K.)
6
49
11
Deformation criterion of the efficiency of strengthening of
welded joints by high-frequency mechanical peening
(Degtyaryov V.A., Shulginov B.S. and Knysh V.V.)
10
Development of inert-gas welding (Review) (Litvinov
A.P.)
Method for evaluation of fracture resistance of welding flux
granules (Golovko V.V. and Goncharov I.A.)
7
3
New flux-cored wire ensuring the effect of strain hardening
of the deposited metal in operation (Malinov L.S., Malinov
V.L., Orlov L.N. and Golyakevich A.A.)
5
New technology for production of joints on high-strength
aluminium alloys by explosion welding (Illarionov S.Yu.,
Dobrushin L.D. and Fadeenko Yu.I.)
11
Nonvacuum electron beam welding of structural steels
(Bach Fr.-W., Beniyash A., Lau K. and Konya R.)
5
Peculiarities of application of split tee-joints in repair and
reconstruction of main pipelines in service conditions (But
V.S., Velikoivanenko E.A. and Olejnik O.I.)
9
Peculiarities of low-amperage argon-arc and microplasma
powder cladding on narrow substrate (Yarovitsyn A.V.,
Yushchenko K.A., Nakonechny A.A. and Petrik I.A.)
6
Effect of carbon on phase composition of weld metal of
welded joints in martensitic steel with 9 % Cr (Skulsky
V.Yu. and Gavrik A.R.)
List of main monographs on explosion welding
2
Effect of composition of base metal and electrode covering
on hygienic properties of welding fumes (Yushchenko K.A.,
Bulat A.V., Levchenko O.G., Bezushko O.N., Samojlenko
V.I., Dovgal D.I. and Kakhovsky N.Yu.)
7
Effect of concentration of hard particles on gas-abrasive
wear resistance of composite alloy (Voronchuk A.P.)
8
Effect of double-jet gas shielding on performance of welded
joints on GL-E36 shipbuilding steel (Chinakhov D.A.)
9
Effect of the centrifugal thermal spraying process on properties of spherical tungsten carbide particles (Dzykovich
V.I.)
4
Efficiency of stabilisation of the alternating-current arc in
covered-electrode welding (Shatan A.F., Andrianov A.A.,
Sidorets V.N. and Zhernosekov A.M.)
3
Photogrammetry applications
(Groeneveld H.D.)
for
explosive
forming
11
Possibility of preservation of shape and size of cylindrical
tubular billets of moulds in explosion cladding (Meshcheryakov Yu.P., Ogolikhin V.M. and Yakovlev I.V.)
11
Evaluation of mechanical properties of microstructural constituents of welded joints (Ishchenko A.Ya. and Khokholova Yu.A.)
1
Producing permanent joints in structured polyethylene
pipes (Korab N.G., Kabysh S.V. and Kostenko A.V.)
6
Evaluation of residual life of welded joints on tank vertical
wall after 20--25 years of service (Barvinko A.Yu.)
5
Production of aluminum--steel bimetal with profiled interface (Bogunov A.Z. and Kuzovnikov A.A.)
11
Experience in designing and manufacture of welding-andsurfacing installations (Titarenko V.I., Tkachenko O.V.,
Matiko D.Yu., Pilipko V.I., Mudraninets I.F. and
Mudraninets I.I.)
3
Repair welding of turbine case parts from heat-resistant
steels without subsequent heat treatment (Tsaryuk A.K.,
Ivanenko V.D., Volkov V.V., Mazur S.I., Trojnyak A.A.,
Vavilov A.V., Kantor A.G. and Volichenko N.P.)
12
Explosive cladding for ITER components (Carton E. and
Stuivinga M.)
11
Some aspects of the technology of high-temperature fluxless
brazing of aluminium alloys (Storchaj E.I., Gorbatsky
Yu.V. and Lantushenko L.S.)
9
Features of laser-MIG welding of high-strength aluminium
alloys (Shelyagin V.D., Khaskin V.Yu., Mashin V.S.,
Pashulya M.P., Bernatsky A.V. and Siora A.V.)
12
TIG welding of thick titanium plates by using forming
backing (Belous V.Yu.)
10
Increase of cyclic fatigue life of tee welded joints with
surface cracks (Knysh V.V., Kuzmenko A.Z. and Solovej
A.S.)
1
Industrial applications of explosion clad (Review) (Banker
J.G.)
To the 60th anniversary of industrial application of the
technology of manufacturing cylindrical tanks from coiled
blanks (Barvinko A.Yu., Barvinko Yu.P. and Golinko
V.M.)
2
11
Trends in development of combined and hybrid welding
and cladding technologies (Litvinov A.P.)
1
Weldability and performance of welded joints (Litvinov
A.P. and Derlomenko V.V.)
9
Welding and cutting 2009. Essen, Germany, 14--19 September 2009
12
Welding repair of surface defects in Ml-10 alloy castings
by using scandium-containing material (Shalomeev V.A.,
Tsivirko E.I., Petrik I.A. and Lukinov V.V.)
3
Widening of technological capabilities of explosion treatment for reducing residual stresses in welded joints on up
to 5000 m 3 decomposers (Lobanov L.M., Dobrushin L.D.,
Bryzgalin A.G., Illarionov S.Yu., Shlensky P.S., Volgin
L.A., Lashkevich V.G. and Grabar E.V.)
11
Influence of joint geometry and fit-up gaps on quality of
corner joints in new modified short arc GMAW (Kah P.,
Martikainen J., Jernstrom P. and Uusitalo J.)
5
Integrated technologies of producing multipurpose layered
composite materials (Trykov Yu.P., Gurevich L.M. and
Shmorgun V.G.)
11
Inverter accelerated voltage source for electron beam welding machines (Chajka N.K.)
6
Laser-submerged arc hybrid welding (Reisgen U. and Olschok S.)
4
Laser welding of titanium alloys (Paton B.E., Shelyagin
V.D., Akhonin S.V., Topolsky V.F., Khaskin V.Yu., Petrichenko I.K., Bernatsky A.V., Mishchenko R.N. and Siora
A.V.)
7
Laser welding of titanium alloys (Paton B.E., Shelyagin
V.D., Akhonin S.V., Topolsky V.F., Khaskin V.Yu., Petrichenko I.K., Bernatsky A.V., Mishchenko R.N. and Siora
A.V.)
50
10
INFORMATION
Domestic agglomerated fluxes for multi-arc welding
10
Moscow Regional Shared Use Explosion Center of the Russian Academy of Sciences (SUEC)
11
12/2009
Technopark «The E.O. Paton Electric Welding Institute»
today
10
NEWS
Branch meeting-conference of «Gazprom» specialists
1
11th International Scientific-practical Conference in St.Petersburg
6
Exhibition «Metals of Siberia: Metallurgy, Machine-Building, Metal-Working, Welding» in Novosibirsk
5
4th International Conference on Laser Technologies
6
International Conference «High Mat Tech»
International Conference «Improvement of turbine plants
using methods of mathematic and physic modelling»
International Conference «Welding and Related Technologies into the Third Millennium»
12
12
2
International exhibition NEVA-2009
10
International exhibition «Weldex/Rossvarka-2009»
12
International Forum on Nanotechnologies
2
International Scientific and Technical Conference «Problems of welding, related processes and technologies»
12
Novokramatorsk Machine-Building Works is 75
10
Opening of commemorative plaques
10
Opening of Russian-German Center of Laser Technologies
9
Petranievsky Readings (devoted to 70th anniversary of creation of UONI-13 electrodes)
8
Seminar on welding technologies «Full readiness to excelent
welding of steel»
12
To Centennial of Birth of G.V. Raevsky
8
To the twenty fifth anniversary of application of welding
in outer space
9
Ukrainian-Belarussian Meeting-Presentation of the Technology of Live Tissue Welding
4
SCIENTIFIC AND TECHNICAL
Analysis of conditions causing initiation and propagation
of corrosion cracks in zones of circumferential joints on
main gas pipelines (Makhnenko V.I., Shekera V.M., Velikoivanenko E.A., Olejnik O.I., Rozynka G.F. and Pivtorak
N.I.)
5
Channel effect in explosion welding (Dobrushin L.D.,
Fadeenko Yu.I., Illarionov S.Yu. and Shlensky P.S.)
11
Control system for beam scanning in electron beam welding
(Lankin Yu.N., Bondarev A.A., Dovgodko E.I. and
Diachenko V.A.)
9
Determination of the parameters of shock-compressed gas
in the welding gap ahead of the contact point in explosion
cladding (Bondarenko S.Yu., Rikhter D.V., Pervukhina
O.L. and Pervukhin L.B.)
11
Development of concepts of the lower boundary of explosion welding of metals (Lysak V.I. and Kuzmin S.V.)
11
Effect of the composition of plasma air-gas mixture on parameters of the plasmatron jet (Pashchenko V.N.)
4
Effect of ultra-dispersed carbides contained in flux-cored
wires on properties of heat-resistant deposited metal (Ryabtsev I.A., Kondratiev I.A., Gadzyra N.F., Davidchuk
N.K., Bogajchuk I.L. and Gordan G.N.)
6
Effectiveness of application of combined magnetic fields in
submerged-arc welding (Nosov D.G. and Razmyshlyaev
A.D.)
4
Efficiency of method for automatic recognition of electrode
imprints in spot welding of three-layer honeycomb structures (Lazorenko Yu.P., Shapovalov E.V., Melnik E.S.,
Lutsenko N.F. and Dolinenko V.V.)
2
Estimation of growth of fatigue cracks in load-bearing
welded structures at random spectrum of cyclic loading
(Makhnenko V.I. and Romanova I.Yu.)
6
Evaluation of susceptibility of welded joints of heat-resistant chromium martensitic steel to cracking at heat treatment (Skulsky V.Yu., Tsaryuk A.K. and Moravetsky S.I.)
1
Features of current inverter design (Moskovich G.N.)
9
Features of explosion welding of titanium to steel in a
shielding atmosphere (Pervukhina O.L., Pervukhin L.B.,
Berdychenko A.A., Dobrushin L.D., Petushkov V.G. and
Fadeenko Yu.I.)
11
Features of resistance welding of titanium aluminides using
nanolayered aluminium-titanium foils (Kuchuk-Yatsenko
V.S., Shvets V.I., Sakhatsky A.G. and Nakonechny A.A.)
3
Features of solidification of complex-alloyed filler metals
for brazing high-temperature nickel alloys (Kurenkova
V.V., Doroshenko L.K. and Malashenko I.S.)
6
Formation of brazed joints on titanium aluminide (Maksymova S.V.)
3
Improved method for calculating magnetic-pulse welding
conditions (Pismenny A.S., Pentegov I.V., Stemkovsky
E.P., ShejkovskyD.A., Kislitsyn V.M. and Lavrenyuk
A.V.)
1
1
Application of mathematical modelling in thermal straightening of shipbuilding panels (Makhnenko O.V.,
Muzhichenko A.F. and Seyffarth P.)
1
Beam current control system in electron beam welding gun
with directly heated cathode (Lankin Yu.N., Sushy L.F.
and Shulym V.F.)
10
Brazing of ferroelectric ceramics in air environment and
pure oxygen atmosphere (Najdich Yu.V., Sidorenko T.V.
and Durov A.V.)
1
Increase of crack resistance of shrouded travelling rolls in
high-speed hardfacing (Chigaryov V.V., Shchetinina V.I.,
Shchetinin S.V., Stepnov K.K., Zavarika N.G. and Fedun
V.I.)
7
Influence of deformation mechanism in the collision zone
of material pairs on selection of optimum parameters of
explosion welding (Bondar M.P.)
11
7
Influence of thermal conditions of welding on the features
of crack initiation in the HAZ of joints of aluminium alloys
V96 and V96tss (Labur T.M., Taranova T.G., Grigorenko
G.M. and Kostin V.A.)
4
Calculation of parameters of longitudinal magnetic field
providing removal of drop from electrode tip in arc surfacing
(Razmyshlyaev A.D. and Mironova M.V.)
Calculation of thermal-deformation conditions of formation
of friction welded joints on heat-resistant alloy EI698VD
(Kuchuk-Yatsenko S.I., Zyakhor I.V., Velikoivanenko
E.A. and Rozynka G.F.)
12/2009
51
Producing permanent joints of γ-TiAl based alloys using
nanolayered Ti/Al interlayer by vacuum diffusion welding
(Ustinov A.I., Falchenko Yu.V., Ishchenko A.Ya.,
Kharchenko G.K., Melnichenko T.V. and Muravejnik
A.N.)
1
7
Risk of cold cracking in welding of structural high-strength
steels (Makhnenko V.I., Poznyakov V.D., Velikoivanenko
E.A., Makhnenko O.V., Rozynka G.F. and Pivtorak N.I.)
12
Investigation of phase transformations and plastic deformation at continuous heating of Al/Cu multilayer foil
(Ustinov A.I., Matvienko Ya.I., Polishchuk S.S. and
Shishkin A.E.)
10
Role of protective coating of aluminium alloy welded joints
in fatigue resistance (Shonin V.A., Mashin V.S., Murashov
A.P., Zelenin V.I., Demianov I.A., Pashulya M.P. and
Teplyuk V.M.)
3
Mechanical impact of gas flow on the surface of penetration
channel walls in gas-laser cutting (Shuba I.V.)
10
Selection of thermal conditions of welding hardening steels
of different structure classes (Skulsky V.Yu.)
6
4
Simulation of temperature fields and stresses in polyethylene pipes in hot-tool welding (Nesterenko N.P., Senchenkov I.K., Chervinko O.P. and Menzheres M.G.)
2
Simulation of the process of electrode metal transfer in
short-circuiting arc welding (Getskin O.B., Erofeev V.A.
and Poloskov S.I.)
2
Strength and structure of aluminium alloy welded joints
made by friction stir and non-consumable electrode welding
(Poklyatsky A.G., Chajka A.A., Klochkov I.N. and Yavorskaya M.R.)
9
Stress-strain state of assemblies of the cylindrical shape in
diffusion bonding (Makhnenko V.I. and Kvasnitsky V.V.)
2
Stress-strain state of welded joints on polymer pipes produced by butt welding at an angle (Nikonova E.S., Korab
N.G. and Kondratenko V.Yu.)
5
Structure and wear resistance of deposited metal
20Kh5M2FS alloyed with sulphur and phosphorus (Ryabtsev I.A., Chernyak Ya.P., Ryabtsev I.I., Zhdanov V.A.
and Bogajchuk I.L.)
10
Structure of phosphorus-containing deposited metal of the
tool steel type (Ryabtsev I.I., Kondratiev I.A., Kostin V.A.,
Novikova D.P., Bogajchuk I.L. and Babinets A.A.)
4
Technological features of electron beam welding of drill
bits (Nesterenkov V.M., Protosej N.E. and Arkhangelsky
Yu.A.)
5
Thermokinetic peculiarities of formation of cold cracks in
welded joints on hardening heat-resistant steels (Skulsky
V.Yu.)
3
Investigation of joints of titanium aluminide with titanium
alloy VT8 produced by diffusion welding (Gorban V.F.,
Kharchenko G.K., Falchenko Yu.V. and Petrushinets
L.V.)
Influence of thermal cycles of welding and external loading
on structural-phase variations and properties of joints of
17Kh2M steel (Markashova L.I., Grigorenko G.M., Poznyakov V.D., Berdnikova E.N. and Alekseenko T.A.)
Microstructure and hardness of Al--Cu alloy (A2218)
welded joints produced by GTAW (Alapati R. and Dwivedi
D.K.)
Modelling and application of high-velocity explosion welding processes (Smirnov G.V., Shuganov A.D., Stefanovich
R.V., Yadevich A.I., Petrov I.V., Kamorny A.A., Konoplyanik V.A., Luchenok A.R., Toloshny A.A., Bogdanovich
P.T. and Dzichkovsky O.A.)
Numerical analysis of characteristics of the arc plasma in
air-vapour plasmatrons with refractory cathode (Krivtsun
I.V., Kharlamov M.Yu., Petrov S.V., Marinsky G.S., Korzhik V.N. and Chernets A.V.)
12
11
10
On the influence of shock wave on welding gap increase in
production of large-sized sheet composites by explosion
welding (Besshaposhnikov Yu.P., Kozhevnikov V.E.,
Chernukhin V.I. and Paj V.V.)
11
Peculiarities of desulphurisation of weld metal in flux-cored
wire welding (Shlepakov V.N. and Naumejko S.M.)
2
Peculiarities of instability of the process of explosion cladding of large-size billets (Silchenko T.Sh., Kuzmin S.V.,
Lysak V.I. and Dolgy Yu.G.)
11
Peculiarities of kinetics of delayed fracture of welded joints
of hardening steels (Skulsky V.Yu.)
7
Peculiarities of structure of metal deposited on edges of single-crystal blades made from nickel superalloys (Yushchenko
K.A., Zadery B.A., Zvyagintseva A.V., Savchenko V.S.,
Gakh I.S. and Karasevskaya O.P.)
8
Peculiarities of utilization of hydrogen-oxygen flame in
flame treatment of materials (Korzh V.N. and Popil Yu.S.)
5
Pressure welding of titanium aluminide to other titanium
alloys (Sabokar V.K., Akhonin S.V., Petrichenko I.K. and
Yasinsky A.V.)
52
12
Index of articles for TPWJ’2009, Nos. 1--12
12
List of authors
12
12/2009